Silky smooth, rich, and creamy with a velvet-like texture is what this Swiss meringue buttercream (SMBC) is all about. Made with just four ingredients the process is fairly simple and easy with no special equipment needed. Use it to frost cakes, pipe on cupcakes, or with fondant-covered cakes.
Table of Content
- Why make this buttercream?
- Ingredients and substitutes
- Swiss meringue buttercream
- Storage
- Tips for success
- How to flavor Swiss meringue buttercream?
- How much buttercream do I need?
- More buttercream recipes
- Troubleshooting Swiss meringue buttercream
- Frequently asked questions
- You may also like
- Printable Recipe
- Join the conversation
I'm very tempted to ask what is your favorite buttercream. But, I love more than one myself, so I'm not going to do that.
In fact, this blog has more than 30 buttercream recipes and it would be so difficult for me to pick one as a favorite. But, I will say that I am a huge buttercream person. And, meringue-based buttercream is one that is very popular with my customers and so easy to make.
Today, I share with you my no-fail recipe with a video and step by step tutorial. In addition, we cover everything you need to know. From the recipe itself, to how to store it, create more flavors, how much do you need for your cake as well as troubleshooting and tips.
Why make this buttercream?
- While American buttercream has two main ingredients, butter, and powdered sugar, meringue buttercream has three main ingredients: egg whites, butter, and sugar (not powdered sugar).
- This means this buttercream is less sweet, and creamier with a velvet-like silky smooth feel on the tongue.
- It holds well on its own and has the perfect consistency for spreading onto cakes or piping onto cupcakes. I personally love them on cupcakes.
- The process is very simple and easy. Plus you do not need any special types of equipment such as thermometers.
- The timeline and process are about 20 minutes
- Separate the egg white from the yolks.
- Make the Swiss meringue
- Add the butter to make the buttercream.
- Flavor it.
Ingredients and substitutes
- Eggs - I like using large eggs as a default for all my baking. Since egg sizes vary dramatically these days, as a guide, a large egg would usually weigh between 50 to 60 grams. Also, it is very important to separate the eggs carefully since you do not want any egg yolks in the whites when making a meringue. In addition, the fat in the yolk will not whip the egg whites properly.
- Cream of tartar - helps stabilize the eggs and works great when making meringue. I highly recommend having some in the house for baking. And yet, if you don't have it, you can omit it completely. Often, vinegar or lemon juice is used as a substitute for COT. But, I usually just omit it in my recipes.
- Sugar - I highly recommend using a fine grain sugar, so it dissolves quicker in the egg whites. And yet, if regular thick sugar is all you have, mix it on the double boiler a litter longer.
- Butter - I like using unsalted butter. And yet, if salted butter is all you have, go ahead and use it. I tried, and it still works.
- Flavoring - Vanilla is always my first flavor of choice, but you can add any other flavoring that you need for the day.
Swiss meringue buttercream
Prepare
- Have all your ingredients at room temperature, especially the eggs and butter.
- Separate the egg whites from egg yolks making sure no egg yolks gets into the whites
Pro tip - break each egg in a separate bowl and use only the ones successfully separated. - Cut the butter into cubes and let come to room temperature
Pro tip - butter must be at room temperature otherwise it will give make a lumpy buttercream. Warmer than room temperature will cause the meringue to deflate.
Swiss meringue
- Place egg whites, sugar, cream of tartar, and salt in the bowl of the stand mixer.
Pro tip - make sure the bowl is grease-free otherwise the egg whites will not whip - Using a whisk, place the bowl over a double boiler and constantly whip until all the sugar has dissolved and the egg whites are fairly warm (about 160 F).
Pro tip - you don't need a thermometer, as long as all the sugar has completely melted your eggs are ready to use
- Take the bowl off the heat and whip the egg whites until you have a thick meringue with stiff peaks. (using the whisk attachment)
Pro tip - it is best to start whipping eggs at medium speed then increase speed as you go for the best meringue - Let the mixer continue to whip on medium-low until the mixer bowl feels cool to touch. Then gradually add butter, one cube at a time, with the mixer at medium speed.
Pro tip - it is VERY important that the meringue is cooled completely before you add the butter otherwise you will have a soupy mess.
Meringue buttercream
- Once all the butter is added, whip on medium-high for 2 minutes.
Pro tip - if the buttercream becomes warm or looks soupy, place the buttercream bowl in the fridge for 10 minutes, then whip with the paddle attachment until light and fluffy. - Lastly, add the vanilla extract and other flavorings. Combine until everything is well combined
Chocolate Swiss Meringue Buttercream
- Add the melted cooled chocolate to the prepared buttercream until it is smooth with no visible white streaks
Pro tip- the chocolate must be cooled before you add it to the buttercream otherwise the warm chocolate will seize when added to the cold buttercream.
Storage
- Meringue Buttercream will keep at room temperature for a few hours in any weather. I know those who enjoy good weather are able to keep Swiss or Italian meringue buttercream out for up to 2 days.
- It should be treated just as butter; If left out at high temperature or humidity it will melt just like butter.
- It can be kept refrigerated for up to one week or in the freezer for up to three months.
- When frozen, it is best thawed in the fridge overnight. Whip with a paddle attachment for about 3 to 5 minutes to restore consistency.
Tips for success
- Preparing the equipment - Grease is the biggest enemy of meringue and the slightest speck on the bowl or whisk could render all your hard work useless. And, it's not just about oil or butter. I'm also talking about egg yolks. Egg yolks have fat and the tiniest amount in your egg whites will not whip into meringue no matter how long you whip.
- So, before you start making any meringue buttercream.
- First, wash and clean the bowl and whisk well (especially if you last used it to make buttercream or similar).
- Then, separate each egg in a small bowl first and use only the eggs which have been separated carefully.
- Save the others for an omelet or other uses.
- Double boiler - Basically, a double boiler is just two pans that fit perfectly together. One on top of the other. We often use this indirect heat method when we want to melt chocolate, or in this case, gently cook eggs with sugar. The steam caused by the water in the bottom pan is just enough to melt the chocolate or egg without burning or overcooking it. I wrote more about double boilers in a previous post - What is a Double Boiler Method?
- Prevent deflating meringue - It is best to start whipping eggs at medium speed then increase speed as you go for the best meringue. This meringue will not lose volume and will hold much better.
- Prevent soupy buttercream - The meringue must be cool completely before you add the butter otherwise you will have a soupy mess.
- White Swiss meringue buttercream- Often, buttercream tends to get a yellow ting, and because of the color of the butter. However, I do not usually have this problem because I do get white butter (see pictures). So, here's a little trick you can use to neutralize the yellow by adding a tiny bit of blue or violet to it. In fact, this is very commonly used when painting walls white. You add a tiny bit of blue or violet to neutralize the yellow. BUT A TINY DAB IS ALL YOU NEED or you will end up with a slight tinge of blue or violet in the buttercream. So, remember, a dap or smear is all you need.
- Prevent separating buttercream - Do not beat buttercream while it is very chilled. Since the cold fat in the butter separates from the liquid and the emulsion you just created breaks. Ideally, you can just let the buttercream rest outside the fridge for a while until it's not hard. Or, you can use a hair-dryer to gently warm the outside of the bowl until you see the edges of the buttercream soften a bit. Then, whip it with a paddle attachment.
How to flavor Swiss meringue buttercream?
- Dark, Milk, or White Chocolate SMBC?
- Add 200 grams of melted and cooled chocolate to 4 cups of SMBC. Combine well.
- Caramel Swiss Meringue Buttercream or Salted Caramel SMBC
- Add 1 cup caramel sauce to 4 (to 6) cups of SMBC. For salted add a tablespoon of rock salt. Combine well.
- Butterscotch SMBC –
- Add 1 cup of butterscotch sauce to 4 (to 6) cups of SMBC. For salted add a tablespoon of rock salt. Combine well.
- Lemon SMBC –
- Add ¼ teaspoon lemon juice to 4 (or 6) cups of buttercream. You can also add up to ½ if you want a very lemony buttercream. 1 teaspoon of zest can also be added if you don’t mind the zest in the buttercream. And, ¼ teaspoon lemon extract will enhance the flavor even more.
- Orange Swiss Meringue Buttercream –
- Add ¼ cup orange juice, and ¼ teaspoon orange extract to 4 (or 6) cups buttercream. 1 teaspoon orange zest can also be added.
- Fruit Flavors – Blueberry, Raspberry, Blackberry, strawberry –
- Add 1 cup fruit puree to 4 (or 6) cups buttercream. I love adding a fruit filling instead, which makes it slightly sweeter, and yet, more vibrant in color.
- Dulce De Leche SMBC –
- Add 1 cup dulce de leche to 4 (6 cups) buttercream.
- Coffee or Espresso SMBC –
- Dissolve 1 tablespoon coffee in ¼ cup hot water or use ¼ cup espresso. Cool completely, then add to 4 (or 6) cups of buttercream.
- Mocha SMBC Buttercream
- Add 200 grams of melted and cooled chocolate to 4 (or 6) cups of coffee SMBC.
- Peanut Butter SMBC
- Add up to 2 cups of peanut butter to 4 (or 6) cups of buttercream.
How much buttercream do I need?
This is a general guide I use for my cakes.
Note: I have given you the filling and frosting separately so you can choose to use other filling with your buttercream. And, if you choose to fill and frost the cake with this - you can use the last column/total.
Also, the amount is in cups - 1 kgs frosting makes about 8 cups.
| Round | Square | Layers | Filling | Frosting | Total |
| 6-inch | 5-inch | 2 | 1.5 Cups | 3 C | 4.5 C |
| 8-inch | 6-inch | 2 | 2 C | 4 C | 6 C |
| 9-inch | 7-inch | 2 | 2.5 C | 5 C | 7.5 C |
| 10-inch | 8-inch | 2 | 3 C | 6 C | 9 C |
| 12-inch | 10-inch | 2 | 5 C | 8 C | 13 C |
| 14-inch | 12-inch | 2 | 7 C | 10 C | 17 C |
| Sheet | 9x13x2 | 1 | 2 C | 5 C | 12 C |
| Tube | 9-inch | 1 | 4 C | 4 C | |
| Cupcake | 12 | 3 C | 3 C |
More buttercream recipes
- Bakery-Style Frosting - Vanilla or Chocolate
- Caramel Buttercream, Butterscotch buttercream
- Eggless Vanilla Buttercream or Chocolate Buttercream
- American, Italian, French, or German Buttercream frosting
- Coffee Buttercream, Eggnog buttercream, White chocolate
- Ermine frosting, Pink champagne buttercream
- See all frosting recipes
Troubleshooting Swiss meringue buttercream
- My eggs got curdled - If you're using a homemade double boiler, make sure the water in the bottom pan does not touch the top pan. You want the steam to touch the pan, not the water. Makes sense? Also, monitor the heat or you will end up with scrambled eggs.
- My buttercream is grainy - Be patient and give the eggs and sugar time to dissolve on medium-low heat. Since, if you crank up the heat you will have sweet scrambled eggs, and also end up with a grainy buttercream if the sugar is not dissolved.
- My buttercream is greasy - When whipping the warm eggs, start on medium and move to high speed. Then, let the meringue whip to stiff peaks. If not, they will lose volume when you add butter giving you a very greasy buttercream.
Also, make sure the meringue is COOL before you add the butter. Check twice or even four times. And, if you are not sure, don't add the butter - give it a minute or two more. - My buttercream is soupy - If the butter is added too early the warm meringue will melt the butter turning the mixture into a meringue soup. DON'T PANIC. Just place the whole mixer bowl in the fridge for 15 to 30 minutes. Then, whip it again. And, if necessary, place it back in the fridge to cool.
- Should I throw my buttercream - NO!! This one breaks my heart every single time. If you think it did not work - don't throw the buttercream - place it in the fridge and send me a comment below- I may be able to help you fix it.
- My buttercream is too buttery - Yes, unlike American buttercreams, meringue buttercreams are buttery. It's essentially sweet whipped egg whites with butter. Light and fluffy in texture but yes, it is buttery and it's ok if you don't like it.
Frequently asked questions
How long can Swiss meringue buttercream keep (sit out?
Both SMBC and IMBC are made with eggs that have been partially cooked over gentle heat which helps stabilize the buttercream. So, both can be stored at room temperature for 2 days, and refrigerated for up to 2 weeks, or in the freezer for up to 2 months.
Can you use Swiss meringue buttercream under fondant?
Yes, absolutely. In fact, one of my favorite buttercream to use under fondant is a meringue-based buttercream, either Swiss or Italian. And, the trick is to make sure you chill the cake really well for a few hours.
- See here how I level, torte, filling my cakes.
- How to cover my cakes with fondant
- See more cake decorating recipes and tutorials here
Is Swiss meringue buttercream safe to eat? What about salmonella?
First, it is always recommended to use pasteurized egg whites. Having said that, not all of us have access to these pasteurized egg white cartons. Therefore, this traditional method of making Swiss meringue buttercream is better.
Sugar starts to dissolve at 140 to 160 C, and the temperature at which the salmonella bacteria is killed is also 160 C. So, the general conclusion is if the sugar has melted in the eggs the mixture has reached 160 C. And so the bacteria if any have been killed.
Can I use meringue powder instead of raw eggs to make this SMBC?
You can, but not using this recipe and process. However, I do have a Swiss meringue buttercream using meringue powder as well. And, I highly recommend you use that recipe.
What is the difference between Italian Meringue and Swiss Meringue Buttercream?
Swiss (SMBC) and Italian (IMBC) are both meringue-based. Hence, they both have whipped egg whites before the addition of butter. And, the main difference between the two is in the process used to make the buttercreams.
- In this SMBC, the egg whites are combined with sugar and heated over a double boiler until all the sugar has melted.
- IMBC, on the other hand, uses a thick sugar syrup that is poured into the whipping egg whites. And, it is very important to use a thermometer to ensure you have the right temperature for the sugar syrup.
- Some say IMBC holds up better in humidity due to the boiling sugar syrup.
Printable Recipe
Swiss Meringue Buttercream SMBC
Print Pin Rate Share by Email Share on FB Save Grow Difficulty: Easy
Diet : GF, NF
Calories: 368kcal
Adjust Servings Here: 6 cups
Description
Silky smooth, rich and creamy with a velvet-like texture is what this Swiss meringue buttercream (SMBC) is all about. Learn to make the best Swiss buttercream with my no-fail recipe. In this recipe post and video tutorial, I tell you everything you need to know about SMBC recipe, including a step-by-step tutorial, how to flavor it, store it, and troubleshoot any possible problems ahead of time.
Video
Conversions Used
1 lb = 453 grams, 1 cup = 240 ml, 1 stick = 113g, 1 tbsp= 15 ml, 1 tsp= 5 ml,
Ingredients
Makes enough to cover 2 x 8-inch cakes or 24 cupcakes
Vanilla
- 6 (180 g) Egg whites ((about ¾ cup))
- 1 cup (200 g) White sugar
- ¼ teaspoon Cream of tartar ((optional))
- 1 lb (450 g) Unsalted butter
- 2 teaspoon Vanilla Extract
- ½ tsp Salt
Chocolate
- 8 oz (225 g) Chocolate (melted cooled)
- ¼ teaspoon Any other flavoring ( almond, strawberry, peppermint, liquor (optional if needed only) )
Instructions
Prepare
- Have all your ingredients at room temperature, especially the eggs and butter.
- Separate the egg whites from egg yolks making sure no egg yolks gets into the whitesPro tip - break each egg in a separate bowl and use only the ones successfully separated.6 Egg whites
- Cut the butter into cubes and let come to room temperaturePro tip - butter must be room temperature otherwise it will give make a lumpy buttercream. Warmer than room temperature will cause the meringue to deflate.1 lb Unsalted butter
Swiss meringue
- Place egg whites, sugar, cream of tartar, and salt in the bowl of the stand mixer.Pro tip - make sure the bowl is grease-free otherwise the egg whites will not whip6 Egg whites, ¼ teaspoon Cream of tartar, ½ teaspoon Salt, 1 cup White sugar
- Using a whisk, place the bowl over a double boiler and constantly whip until all the sugar has dissolved and the egg whites are fairly warm (about 160 F).Pro tip - you don't need a thermometer, as long as all the sugar has completely melted your eggs are ready to use
- Take the bowl off the heat and whip the egg whites until you have a thick meringue with stiff peaks.Pro tip - it is best to start whipping eggs at medium speed then increase speed as you go for the best meringue
Meringue buttercream
- Let the mixer continue to whip on medium-low until the mixer bowl feels cool to touch. Then gradually add butter, one cube at a time, with the mixer at medium speed.Pro tip - it is VERY important that the meringue is cooled completely before you add the butter otherwise you will have a soupy mess.
- Once all the butter is added, whip on medium-high for 2 minutes. Pro tip - if the buttercream becomes warm or looks soupy, place the buttercream bowl in the fridge for 10 minutes, then whip with the paddle attachment until light and fluffy.1 lb Unsalted butter
- Lastly, add the vanilla extract and other flavorings. Combinel until everything is well combined2 teaspoon Vanilla Extract
Chocolate Swiss Meringue Buttercream
- Add melted cooled chocolate to prepared buttercream until it is smooth with no visible white streaksPro tip- the chocolate must be cooled before you add it to the buttercream otherwise the warm chocolate will seize when added to the cold buttercream.8 oz Chocolate
Recipe Notes & Tips
- Preparing the equipment
- Grease is the biggest enemy of meringue and the slightest speck on the bowl or whisk could render all your hard work useless. And, it's not just about oil or butter. I'm also talking about egg yolks. Egg yolks have fat and the tiniest amount in your egg whites will not whip into meringue no matter how long you whip.
- So, before you start making any meringue buttercream. First, wash and clean the bowl and whisk well (especially if you last used it to make buttercream or similar). Then, separate each egg in a small bowl first and use only the eggs which have been separated carefully. Save the others for an omelet or other uses.
- Double boiler
- Basically, a double boiler is just two pans that fit perfectly together. One on top of the other. We often use this indirect heat method when we want to melt chocolate, or in this case, gently cook eggs with sugar. The steam caused by the water in the bottom pan is just enough to melt the chocolate or egg without burning or overcooking it. I wrote more about double boilers in a previous post - What is a Double Boiler Method?
- Prevent deflating meringue
- It is best to start whipping eggs at medium speed then increase speed as you go for the best meringue. This meringue will not lose volume and will hold much better.
- Prevent soupy buttercream
- The meringue must be cool completely before you add the butter otherwise you will have a soupy mess.
- White Swiss meringue buttercream
- Often, buttercream tends to get a yellow ting and because of the color of the butter. However, I do not usually have this problem because I do get white butter (see pictures). So, here's a little trick you can use to neutralize the yellow by adding a tiny bit of blue or violet to it.
In fact, this is very commonly used when painting walls white. You add a tiny bit of blue or violet to neutralize the yellow. BUT A TINY DAB IS ALL YOU NEED or you will end up with a slight tinge of blue or violet in the buttercream. So, remember, a dap or smear is all you need.
- Often, buttercream tends to get a yellow ting and because of the color of the butter. However, I do not usually have this problem because I do get white butter (see pictures). So, here's a little trick you can use to neutralize the yellow by adding a tiny bit of blue or violet to it.
- Prevent separating buttercream
- Do not beat buttercream while it is very chilled. Since the cold fat in the butter separates from the liquid and the emulsion you just created breaks. Ideally, you can just let the buttercream rest outside the fridge for a while until it's not hard. Or, you can use a hair-dryer to gently warm the outside of the bowl until you see the edges of the buttercream soften a bit. Then, whip it with a paddle attachment.
Storage
- Meringue Buttercream will keep at room temperature for a few hours in any weather. I know those who enjoy good weather are able to keep Swiss or Italian meringue buttercream out for up to 2 days.
- It should be treated just as butter; If left out in high temperature or humidity it will melt just like butter.
- It can be kept refrigerated for up to one week or in the freezer for up to three months.
- When frozen, it is best thawed in the fridge overnight. Whip with a paddle attachment for about 3 to 5 minutes to restore consistency.
Buttercream Flavors
- Dark, Milk, or White Chocolate SMBC?
- Add 200 grams melted and cooled chocolate to 4 cups of SMBC. Combine well.
- Caramel Swiss Meringue Buttercream or Salted Caramel SMBC –
- Add 1 cup caramel sauce to 4 (to 6) cups of SMBC. For salted add a tablespoon of rock salt. Combine well.
- Butterscotch SMBC –
- Add 1 cup butterscotch sauce to 4 (to 6) cups of SMBC. For salted add a tablespoon of rock salt. Combine well.
- Lemon SMBC –
- Add ¼ teaspoon lemon juice to 4 (or 6) cups buttercream. You can also add up to ½ if you want a very lemony buttercream. 1 teaspoon of zest can also be added if you don’t mind the zest in the buttercream. And, ¼ teaspoon lemon extract will enhance the flavor even more.
- Orange Swiss Meringue Buttercream –
- Add ¼ cup orange juice, and ¼ teaspoon orange extract to 4 (or 6) cups buttercream. 1 teaspoon orange zest can also be added.
- Fruit Flavors – Blueberry, Raspberry, Blackberry, strawberry –
- Add 1 cup fruit puree to 4 (or 6) cups buttercream.
I love adding a fruit filling instead, which makes it slightly sweeter, and yet, more vibrant in color.
- Add 1 cup fruit puree to 4 (or 6) cups buttercream.
- Dulce De Leche SMBC –
- Add 1 cup dulce de leche to 4 (6 cups) buttercream.
- Coffee or Espresso SMBC –
- Dissolve 1 tablespoon coffee in ¼ cup hot water or use ¼ cup espresso. Cool completely, then add to 4 (or 6) cups buttercream.
- Mocha SMBC Buttercream
- Add 200 grams melted and cooled chocolate to 4 (or 6) cups coffee SMBC.
- Peanut Butter SMBC
- Add up to 2 cups of peanut butter to 4 (or 6) cups of buttercream.
Nutrition Information
Calories: 368- kcalCarbohydrates: 31.5- gProtein: 3.8- gFat: 25.8- gSaturated Fat: 16.1- gPolyunsaturated Fat: 9.7- gMonounsaturated Fat: 0- gTrans Fat: 0- gCholesterol: 50- mgSodium: 51- mgPotassium: 0- mgFiber: 0- gSugar: 31.4- gVitamin A: 0- IUVitamin C: 0- mgCalcium: 0- mgIron: 0- mg
The nutrition information and metric conversion are calculated automatically. I cannot guarantee its accuracy. If this data is important to you please verify with your trusted nutrition calculator. Thank you
Did you make this recipe? Share it with me.Tag @veenaazmanov on instagram or #hashtag it #veenaazmanov
Debra
I am new to making this buttercream, and I have not been sucessful. My first time I did not wash everything down with vinegar so I assume that was why the meringue didn't make it to stiff peaks . The next time I washed down everything I was using, but I still couldn't get to stiff peaks . What could I be doing wrong? Sugar crystals??
Veena Azmanov
Debra, I'm sorry to hear that. Well, let's see.
1. make sure to separate the eggs properly. Any, yolk (even the tiniest bit) is fat!
2. Clean equipment but don't saturate them with vinegar. Just barely wipe them dry. Vinegar can cook the eggs
3. make sure the eggs are at room temperature but also don't over temper the eggs. It takes just minutes to temper.
4. start at a low speed and then increase speed gradually. Otherwise, they will start to whip and them loose volume quickly.
I hope these tips help.
Anushri
Hello Veena, i always loved your recipes. Especially this SMBC , it’s very light in sweet. Does this recipe works with pasteurized egg white? My heart always break while throwing egg yolks 😣. Can’t eat so much yolks , as I bake professionally, I make bigger batches @ freeze it most of the time. Thank you so much 😊
Veena Azmanov
Thank you, Anushri. I do have a recipe for SMBC with meringue powder. Warming the egg whites is essentially pasteurizing them so technically, you could just add the sugar gradually to the whipping egg whites and then add the butter. Do a small batch and see how it goes. Tweak as needed.
Imelda
Hi Veena,
Thank you for your advice not to give up or throw away the buttercream if it’s not going well. I had mine look curdled and almost threw it away but I finally found the solution from your post.
I read from one of the comments that you can substitute the butter with cream cheese. What is the ratio for this recipe? I tried adding cream cheese on top of the original SBM recipe last time but it became soft. I don’t what went wrong.
Thanks in advance!
Veena Azmanov
Imelda. Yes,chilling for a few minutes usually does the trick.
For cream cheese. I use half butter and half full-fat cream cheese (usually 40% mascarpone)
I add it at the end after I have whipped the buttercream.
Make sure the cream cheese is room temperature and creamy (to prevent lumps) Then add it and whip until smooth.
Do not overwhip once you add cream cheese as it can curdle with the meringue.
Samantha
Can you help me troubleshoot?
The frosting looked perfect until I added the butter. Now it looks just like cottage cheese. I put it in the fridge. Is there anything I can do to fix it?
Veena Azmanov
Hey Samantha. Yes, putting it in the fridge is the right thing to do at this point. The reason the buttercream looks like cottage cheese simply means that the bowl was still not completely cold when you added the butter. So it melted slightly and looks curdled. Let it cool for a few minutes until whip it until smooth