Roast Lamb with Potato Onion and Pepper Gratin

Elevate your next dinner party with this show-stopping Roast Lamb with Potato, Onion, and Pepper Gratin—a savory celebration of bold flavors and comforting textures. This recipe pairs a succulent, herb-infused leg of lamb roasted to perfection with a decadent gratin layered with golden potatoes, sweet onions, and vibrant red bell peppers, all baked in a creamy, nutmeg-spiced sauce. Topped with Parmesan cheese for a golden, bubbling crust, this dish seamlessly blends hearty, rustic charm with refined elegance. Perfect for special occasions or Sunday roasts, this one-pan wonder lets you roast the lamb and gratin together, making it a stress-free way to impress. Serve this stunning centerpiece alongside a fresh green salad or roasted vegetables for a complete, unforgettable meal.

Nutriscore Rating: 59/100

Prep Time:30 mins

Cook Time:120 mins

Total Time:150 mins

Servings: 6

Ingredients

• 1 whole (approximately 4-5 lbs) leg of lamb
• 4 pieces garlic cloves
• 4 sprigs fresh rosemary
• 4 tablespoons olive oil
• 2 teaspoons sea salt
• 1 teaspoon black pepper
• 4 large yellow potatoes
• 1 large yellow onion
• 1 large red bell pepper
• 1.5 cups heavy cream
• 1 cup grated Parmesan cheese
• 2 tablespoons butter
• 0.25 teaspoon nutmeg

Directions

Step 1

Preheat your oven to 375°F (190°C).

Step 2

Prepare the lamb by making small incisions all over the surface using a small knife.

Step 3

Insert a slice of garlic and a small sprig of rosemary into each incision.

Step 4

Rub the leg of lamb with 2 tablespoons of olive oil, sea salt, and black pepper. Set aside to marinate while preparing the gratin.

Step 5

Peel the potatoes and slice them thinly (about 1/8-inch thick). Similarly, slice the onion and red bell pepper into thin rings.

Step 6

Grease a medium-sized baking dish with 1 tablespoon of butter.

Step 7

Layer the potato slices, onion slices, and red bell pepper rings in the baking dish, alternating as you go.

Step 8

In a small bowl, whisk together the heavy cream, nutmeg, and a pinch of salt and pepper. Pour this mixture evenly over the layered vegetables.

Step 9

Sprinkle the grated Parmesan cheese over the top of the gratin.

Step 10

Cover the baking dish with aluminum foil and place it in the oven on a lower rack.

Step 11

Place the prepared lamb on a roasting rack in a large roasting pan. Insert a meat thermometer into the thickest part of the lamb, but not touching the bone.

Step 12

Roast the lamb and gratin simultaneously in the oven. Check the lamb’s internal temperature after 90 minutes—it should reach 135°F (57°C) for medium-rare or 145°F (63°C) for medium.

Step 13

When the lamb is fully cooked, remove it from the oven, tent it with aluminum foil, and allow it to rest for 15 minutes.

Step 14

Remove the foil from the gratin and move it to the top rack. Increase the oven temperature to 400°F (200°C) and allow the gratin to bake uncovered for another 10-15 minutes until golden and bubbling.

Step 15

Slice the lamb and serve alongside portions of the potato, onion, and pepper gratin.

Nutrition Facts

Serving size	(3652.9g)

Amount per serving	% Daily Value*
Calories	8945.3

Total Fat 648.7g	0%
Saturated Fat 294.0g	0%
Polyunsaturated Fat 6.0g
Cholesterol 2445.8mg	0%
Sodium 7786.6mg	0%
Total Carbohydrate 190.6g	0%
Dietary Fiber 21.6g	0%
Total Sugars 19.1g
Protein 563.4g	0%

Vitamin D 4.5IU	0%
Calcium 1402.5mg	0%
Iron 47.0mg	0%
Potassium 10265.8mg	0%

*The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.

Source of Calories

Fat: 65.9%

Protein: 25.5%

Carbs: 8.6%