Roast Leg of lamb – Garlic Butter Marinade
This is how to roast a leg of lamb perfectly every single time. With a simple garlic butter marinade, this meat is tender, juicy, and cooked to perfection. Serve with a side and bread for a complete meal. Leftovers are great for sandwiches and wraps.
Are you afraid of roasting meat? Especially cuts like a leg or a lamb shoulder? Well, don’t be. In fact, they are easy once you know the right method and technique.
The one thing that gave me confidence in roasting was buying my meat thermometer. In fact, I highly recommend you buy this one. This takes the guesswork out. It means that you don’t have to calculate the meat and the cooking time. Also, it means you don’t have to open the oven door every time to check on it. In addition, the best thing is that you are no longer stressed.
Why make this leg of lamb
- This is the easiest, no-fuss roast lamb to make any time of the year. Plus, there is so much to love about this roast.
- Today, I am using a garlic butter marinade, but you can use the same process to roast lamb successfully every single time, no matter what marinade you use.
- You can marinate the meat for as little as 15 minutes to an hour or up to 12 hours in the fridge.
- Today, I am using bone-in lamb leg, but you can also use boneless leg of lamb or lamb shoulder with this marinade.
Timeline for making this lamb
Knowing how long your dish will take is important when planning a meal. Remember that you can use the oven at the same time.
- Make the garlic herb marinade – 10 mins
- Marinate the lamb – 15 mins up to 12 hours.
- Roast the lamb – 60 to 90 mins
- Rest the lamb – 15 mins
- Make gravy – 10 mins
Ingredients and substitutes
- Lamb—I am using a bone-in leg of lamb, but you can also use the shoulder for this recipe. Just make sure to thaw the meat an hour or two before roasting.
- Butter – Adds flavor and keeps the lamb moist and tender. Plus, the gravy is absolutely delicious.
- Herbs—Fresh herbs are very important for marinating red meat. However, you can also use 1 tsp dry rosemary and 1 tsp dry thyme in the marinade.
- Garlic—This has to be fresh garlic. As you can see, we have a generous portion of garlic for flavor.
How to roast a leg of lamb
- Marinade – In a small bowl, combine butter, garlic, thyme, rosemary, salt, and pepper
- Lamb – Trim excess fat off the lamb and pat dry on all sides.
Pro tip – If the lamb is wet, the marinade will slide off the meat as soon as it starts cooking. If the meat is frozen, ensure it is thawed for at least an hour before marinating. - Season the lamb with salt and pepper. Then, marinate it with the garlic butter marinade.
Pro tip – Leave to marinate for an hour on the counter or up to 12 hours in the fridge. This recipe can be roasted even without marinating, but it is always recommended if you have the time.
- Preheat the oven to 350°F / 180°C / Gas mark 4
- Place the leg of lamb in a roasting pan on the roasting rack.
Pro tip – If you’re using a thermometer like me, add it in the center of the thickest part of the meat. - Add 1/4 cup of water to the roasting rack.
Pro tip– Adding the water will prevent the melted butter marinade from burning/smoking as it drips into the pan.
- Roast until you reach the desired temperature of doneness:
- Medium rare – between 130°F and 135°F, approximately 20 minutes per pound.
- Medium – between 135 F to 140 F, approximately 22 to 23 minutes per pound
- and Medium well – between 145 F to 150 F, approximately 25 minutes per pound
- Well Done is between 155 and 165°F, approximately 30 minutes per pound.
- When the thermometer reaches your desired temperature, remove the lamb from the oven. Loosely tent it with aluminum foil and let it rest for at least 15 minutes before slicing. In the meantime, make the gravy.
Gravy
- Place the roasting pan over medium heat and add the stock. Deglaze the pan by scraping off as much as you can from the pan.
Pro tip – Use a wooden or silicone spatula so you don’t ruin our roasting rack. Do not scrape the burnt black parts just to avoid adding a burnt taste to the gravy. - Add the flour and continue to cook until it thickens. Strain through a sieve or mesh to remove all the unwanted herbs, etc. Serve alongside the meat.
Sides to go with this leg of lamb
Frequently asked questions
If stored properly, a roast leg of lamb will keep in the fridge for 3 to 4 days. You can also freeze it for up to a month.
A leg of lamb can be boneless or bone-in. It is a very impressive and often expensive cut of meat that comes from the back haunches of the lamb.
As a guide, look for an average weight of about 5 to 7 pounds. Don’t buy a baby lamb or an old lamb that may be too tough when cooked.
Also, ask the butcher to trim the outer tough layer of fat. But don’t remove all the fat; you need some for flavor and to keep the meat moist and tender.
I prefer to use a meat thermometer, so I don’t have to calculate and watch the clock so often. But you can certainly do without it. A thermometer can take the guesswork out if you are new to cooking or roasting meat. The most important point to note is to make sure you insert the thermometer needle in the middle, the deepest part of the thick meat.
I cook my lamb medium rare, about 135°F, using a meat thermometer. But if you don’t own a thermometer, here’s a guide you can use.
– Medium rare – between 130°F to 135°F, approximately 20 minutes per pound.
– or Medium – between 135°F to 140°F, approximately 22 to 23 minutes per pound.
– and Medium well – between 145°F to 150°F, approximately 25 minutes per pound.
– Well Done is between 155 to 165 F, approximately 30 minutes per pound
Roast Leg of Lamb – Garlic Butter Marinade
This is how to roast a leg of lamb perfectly every single time. With a simple garlic butter marinade, this meat is tender, juicy, and cooked to perfection. Serve with a side and bread for a complete meal. Leftovers are great for sandwiches and wraps.
Video
Ingredients
- 5 lbs (2.25 kg) Leg of lamb (bone in)
- 4 tbsp (55 g) Butter unsalted
- 6 – 8 large Garlic cloves finely minced
- 2 sprig Rosemary leaves removed, chopped
- 4 sprigs Thyme leaves removed, chopped
- 1 tsp Salt
- 1 tsp Pepper
- 1 tbsp All-purpose flour
- ½ cup (120 ml) Stock (or white wine)
Method
- Marinade – In a small bowl, combine butter, minced garlic, thyme, rosemary, salt, and pepper.4 tbsp Butter, 6 – 8 large Garlic cloves, 2 sprig Rosemary, 4 sprigs Thyme, 1 tsp Salt, 1 tsp Pepper
- Lamb – Trim excess fat off the lamb and pat dry on all sides.5 lbs Leg of lamb
- Season the lamb with salt and pepper. Then, marinate it with the garlic butter marinade.
- Preheat the oven at 350°F / 180°C / Gas mark 4
- Place the leg of lamb in a roasting pan on the roasting rack.
- Add 1/4 cup water to the roasting rack.
- Roast until you reach the desired temperature of doneness.– Medium rare – between 130 F to 135 F, approximately 20 minutes per pound.– Medium – between 135 F to 140 F, approximately 22 to 23 mins per pound – Medium well – between 145 F to 150 F, approximately 25 minutes per pound– Well Done is between 155 to 165 F, approximately 30 minutes per pound.
- When the thermometer reaches your desired temperature, remove the lamb from the oven. Loosely tent it with aluminum foil and let it rest for at least 15 minutes before slicing. In the meantime, make the gravy.
- Place the roasting pan over medium heat and add the stock. Deglaze the pan by scraping off as much as you can from the pan.1 tbsp All-purpose flour, ½ cup Stock
- Add the flour and continue cooking until it thickens. Strain through a sieve or mesh to remove all the unwanted herbs, etc. Serve alongside the meat.
Notes
- You want to choose a well-marbled piece of meat with a decent amount of fat on top. The fattier the meat, the more juicy and flavorful the roast.
- Always thaw the lamb before cooking – at least 2 to 3 hours. Cooking chilled meat can result in uneven baking, causing the outer parts of the meat to overcook.
- A leg is a large chunk of meat that is exposed a little. So, make sure to over-season the meat, as only some of it will penetrate. The rest will get crusted on.
- Use a roasting rack; don’t just place the meat on the baking tray. The roasting rack will let the juices flow below and let the outside of the leg form a crust, almost a sear, that keeps all the juices in.
- Elevate the bone from the base if possible. This encourages even cooking by circulating the air.
- Cook the meat just until you reach the desired doneness, not a minute more. The meat continues to cook to about 5 to 10 degrees more after you take it out of the oven.
- If you are entertaining and want to ensure the perfect roast, remove the lamb at about 135 F. It will be perfectly pink and about 140 F by the time you serve.
- Don’t open the oven door too often to check doneness. Instead, calculate the cooking time and check closer to the time.
- Don’t poke too many holes in the meat while checking for doneness. When you poke a hole in the meat, you will see juices flow out. You want these to stay in, so don’t make too many holes. I poke the thermometer just once and leave it there until it reaches the desired temperature.
- Let the meat rest after cooking. If you cut the meat too soon, all the juices will flow out of it, giving you a dry roast. Instead, let the meat rest for at least 15 minutes, if not more.
Cooking temperatures and time for lamb
I cook my lamb medium-rare, about 135 F using a meat thermometer. Here’s a handy guide to use.- Medium rare – between 130 F to 135 F, approximately 20 minutes per pound.
- Medium – between 135 F to 140 F, approximately 22 to 23 minutes per pound.
- Medium well – between 145 F to 150 F, approximately 25 minutes per pound.
- Well Done is between 155 to 165 F, approximately 30 minutes per pound.
Equipment you will need
Nutrition
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Great site! I’m glad I found it, as I have to cook for some friends. Small question… are you sure the marinade recipe calls for 6 ‘cloves’ of garlic? wouldn’t it be better to crush them, slice them, or mince them? I’m quite new to cooking, just asking…
Hey Alf, Yes, as you can see in the progress pictures and the video, the garlic is minced, and the leaves are finely chopped. There is a video in the post, too, so you can see the process. If you are new, both of these should be very helpful. Let me know how it goes.
My family loves roasted lamb. It’s probably one of our favorite Sunday dinner options during the colder winter months. Your recipe sounds so delicious. I never used thyme for a lamb before. I will definitely give it a try next time I’m roasting a lamb.
Thanks, Natalie. I hope you try it soon.
I’ve never roasted a leg of lamb but your recipe and step by step instructions make it seem all very easy and approachable. Lamb and be intimidating (speaking from experience) but you may have convinced me to give it a try!
I am so happy to hear that, Nicole. I hope you try. It really is easy. Thanks
Garlic butter marinade?! No way. I’m sold. Thanks for all the tips! I’ve never cooked lamb before so they’re super useful.
It is very easy Erin. You must try.
We love lamb but I’ve always been too intimidated to try roasting a whole leg of lamb. This gives me confidence.
I am so happy to hear that. Thank you Andrea
It doesn’t seem like a celebration unless we have a delicious roasted leg of lamb. You give such great hints and it’s exactly how we do it. You don’t want to cook it until it’s a scab – you have it cooked to at ideal temperature. And Lamb would not be lamb without rosemary. Great post.
Thanks Marisa. Glad you liked it