Italian Meringue Buttercream (IMBC)

Silky smooth, light, and fluffy this Italian meringue buttercream is less sweet and more buttery than standard buttercream. 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.

Once you've tired a meringue-based buttercream it's almost impossible to go back to any other.

As a cake decorator, I have lost count of how many cakes I frosted with buttercream. As a cake instructor, I have taught many students to make a variety of buttercream recipes - American, Swiss, Italian, French, German, and more.

The one buttercream that most students have issues with is this Italian method. This is why today, you get a detailed recipe, my no-fail method, step-by-step progress pictures as well as a video tutorial. Included below are tips, FAQ, troubleshooting, and everything you need to know.

Why make this buttercream?

• The Italian meringue method is a little more complicated because you do need a candy thermometer to boil the sugar syrup. And yet, this method adds stability to the meringue keeping it fluffy longer.
• For those of you new to meringue buttercreams it is usually less sweet, creamier with a velvet-like silky smooth feel on the tongue
• Similar to Swiss meringue it's also much lighter because it has whipped egg whites which adds volume along with butter and sugar.
• It holds well on its own and has the perfect consistency for spreading onto cakes or and piping onto cupcakes. I personally love them on cupcakes.
• The timeline and process is very simple
  • Separate egg white from yolks.
  • Boil the sugar syrup.
  • Whip the meringue.
  • Pour hot syrup into the meringue.
  • Let the meringue cool.
  • Add the butter.
  • Whip the buttercream some more.
  • Flavor it...
  • Learn how to torte, fill, and frost a cake like a pro.

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 weight between 50 to 60 grams. It is very important to separate the eggs carefully as you do not want any egg yolks in the whites when making the meringue. Also, the fat in the white will not whip the egg whites properly.
• Cream of tartar - Gives a much creamier egg white and it prevents the separation of protein and water in the whites. It's also flavorless, so it does not affect the flavor. The best substitute for cream of tartar is a pinch of salt, but lemon juice and vinegar are often used.
• Sugar - I highly recommend using a fine grain sugar so the syrup comes to temperature quickly.
  Pro tip - you can pulse thick grain sugar in the food processor but do not powder it.
• Butter - Unsalted butter is the best for all baking and desserts. It keeps you in control of the amount of salt in the recipe. This will still work with salted butter as long as you omit salt in the recipe. Most salted butter also has a yellow color which will affect the color of your buttercream.
• Flavoring - Vanilla is always my first flavor of choice, after that, I add any additional flavoring. You can reduce the quantity of vanilla and use a combination of other flavorings.

Step by step instructions

Makes enough to cover 2 x 8-inch cakes or 24 cupcakes

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 room temperature otherwise it will give make a lumpy buttercream. Warmer than room temperature will cause the meringue to deflate.

Sugar syrup

• Heat sugar and water in a heavy bottom light colors saucepan over medium heat. Once all the sugar is melted place a candy thermometer inside.
  Pro tip - using a heavy-bottom will distribute heat evenly and prevent the sugar caramelizing and a light-colored pan means you can see the color of the sugar and as you work.
• Continue to boil until the sugar syrup reaches about 238 F on the candy thermometer (softball stage)
  Pro tip - This takes about 5 to 7 minutes on medium heat. Keep a close eye so you don't caramelize it.

Whip egg whites (while the sugar syrup is cooking)

• Place egg whites, salt, and cream of tartar in the bowl of a stand mixer with the whisk attachment on medium speed.
  Pro tip - while this can be made with a hand mixer, if you do own a stand mixer I highly recommend using the stand mixer. This does need some good whipping
• After 2 minutes, your meringue should be at the soft peak stage.
  Pro tip - The meringue should hold soft peaks but still look shiny, not dry. Whipping too quickly on high will cause it to be dry and later lose volume.
• Once the meringue is at the soft peak stage - turn the mixer off to avoid over mix and wait for the sugar to reach temperature

Pour hot syrup into the meringue

• Turn the mixer with the meringue to medium and watch the sugar syrup for temperature closely.
• Start pouring the hot sugar syrup into the mixer bowl. The sugar should stream between the whisk and the edge of the bowl.
  Pro tip - It is not necessary to run the mixture on high while you pour the syrup. Stay in control use medium speed and a steady slow pour making sure it is between the whisk and the bowl edges.
• Once all the syrup is in. Turn the mixer on high and whisk for about 3 minutes. The outside of the bowl will be hot at first and then be barely warm.
• Your meringue should now look shiny and stiff. Let the mixer run on low until the bowl feels cold to the touch.
  Pro tip - it's ok to let the mixer run on low and let the meringue cool down. In warmer places, you can also place the mixer in the fridge for 5 minutes to prevent it from losing volume.

Adding the butter

• When the meringue is cold and the bowl is not warm at all. Start adding the butter - one cube at a time.
  Pro tip - This is where 90% of meringue buttercreams fail DO NOT add butter if the meringue is still not cold. It should not even be barely warm. Walk away from the mixer, go get a drink.
• Once all the butter is in whip for another minute or two until you have a smooth and satin-like buttercream that light and fluffy.
  Pro tip - if you feel the meringue has lost volume and looks like a soup. It means the meringue was not cold and the butter melted. Stop the mixer and place the bowl in the fridge for 10 to 15 minutes. Then whip again and it should whip back its consistency.
• Finally, add vanilla or any other flavoring you want

Storage

• Meringue buttercream will keep at room temperature for 2 to 3 days. 
• It should be treated just like 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 two months.
• When frozen it is best thawed in the fridge overnight.
• Whip with a paddle attachment for about five minutes to restore consistency

How to flavor Italian meringue buttercream?

• Dark, Milk, or White Chocolate  - Add 200 grams melted and cooled chocolate to 4 cups of IMBC. Combine well. 
• Caramel or Salted Caramel IMBC- Add 1 cup caramel sauce to 4 (to 6) cups of IMBC. For salted add a tbsp of rock salt. Combine well. 
• Butterscotch - Add 1 cup butterscotch sauce to 4 (to 6) cups of IMBC. For salted add a tbsp of rock salt. Combine well. 
• Lemon  - Add ¼ tsp lemon juice to 4 (or 6) cups buttercream. You can add up to ½ if you want a very lemony buttercream. 1 tsp of zest can also be added if you don't mind the zest in the buttercream. ¼ tsp lemon extract will enhance the flavor even more. 
• Orange - Add ½ cup orange juice,  ¼ tsp orange extract to 4 (or 6) cups buttercream. 1 tsp orange zest can be added too. 
• 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 but also more rich and vibrant in color. 
• Dulce De Leche - Add 1 cup dulce de leche to 4 (6 cups) buttercream. 
• Coffee or Espresso -   Dissolve 1 tbsp coffee in ¼ cup hot water or use ¼ cup espresso. Cool completely then add to 4 (or 6) cups of buttercream
• Mocha  - Add 200 grams melted and cooled chocolate to 4 (or 6) cups coffee IMBC 
• Peanut butter - Add up to 2 cups 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 another 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

Frequently asked questions

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