LAMB AU GRATIN

Steps:

• Preheat oven to 375 degrees F (190 degrees C). Thoroughly grease a covered baking dish.
• Heat a large skillet over medium-high heat. Cook and stir ground lamb in the hot skillet until some of the fat begins to render; add onion, carrots, and garlic. Continue to cook and stir the mixture until the lamb is completely browned and crumbly, 5 to 7 minutes. Stir soup mix into the lamb mixture; remove skillet from heat.
• Melt butter in a saucepan over medium heat. Whisk flour into butter, 1 tablespoon at a time, making sure there are no lumps between additions. Pour milk into the butter mixture while whisking; continue to whisk until the milk thickens and the mixture is smooth.
• Switch heat below saucepan to 'off.' Stir Cheddar cheese and Havarti cheese into the milk mixture until the cheese is melted and the sauce is smooth.
• Spoon a small amount of the cheese sauce into the beaten egg in a bowl; whisk together to temper the egg. Pour the tempered egg into the cheese sauce and stir.
• Arrange sliced potatoes in the bottom of the prepared baking dish, overlapping to make a layer about 1/2-inch deep; season with salt and pepper. Pour about 1/3 of the cheese sauce over the potatoes and spread into an even layer. Spread the lamb mixture evenly atop the cheese sauce layer. Layer remaining potatoes atop the lamb; season again with salt and pepper. Pour remaining cheese over the top. Cover baking dish.
• Bake in preheated oven until the potatoes are tender, about 90 minutes. Remove cover and continue baking until the top browns, about 30 minutes more.