Wondering what to do with leftover lamb roast? Our ultimate Leftover Lamb Shepherd's Pie is a great recipe to make with the leftovers from your lamb roast. Add mashed potatoes and transform them into this easy casserole!

This shepherd's pie is an easy dinner the whole family will love. Topped with soft and fluffy mashed potatoes, and then baked in the oven until golden and crispy, you'll fall in love from the first bite!

WHY YOU'LL LOVE THIS RECIPE: – It's a delicious twist on a childhood favorite. – This shepherd's pie is such an easy recipe! It's also a great way to deal with leftover lamb roast. – This pie will save you both time and money, and who doesn't like that?

LAMB FILLING INGREDIENTS:Olive oil: You will need some olive oil to sauté the onions. – Onion: I prefer using white onion, but yellow and red onions are great too. – Carrot: Carrots make a great addition to the lamb filling. Peel and finely dice your carrots. ( You can also use 1 cup of frozen mixed peas & carrots if you like.)

LAMB FILLING INGREDIENTS – Garlic: Garlic adds a kick of flavor to the lamb filling. – Herbs: Fresh parsley and dry or fresh rosemary add a kick of flavor to the pie filling. – Leftover roast lamb: Shred or chop the leftover roast lamb into bite-size pieces. – Worcestershire sauce: Don't skip this sauce. It is a fantastic way to infuse a ton of extra flavor.

LAMB FILLING INGREDIENTSAll-purpose flour: You will need flour to thicken the sauce. – Tomato paste: Tomato paste adds a richer flavor and hint of tomato. – Broth: You can use chicken stock, beef stock, lamb stock, vegetable broth, or leftover gravy. – Salt and black pepper

POTATO TOPPING:Russet potatoes:  Russet potatoes are the best choice for the shepherd's pie. Peel and cut the potatoes into 1-inch cubes. – Parmesan cheese: Adding some grated parmesan cheese to the potato topping will make your pie more delicious. – Heavy cream: Don't skip the heavy cream. It adds creaminess to the potatoes.

POTATO TOPPING:Egg: The egg adds some creaminess and structure to the potatoes. – Butter: You need butter for the mashed potatoes and some for drizzling before baking. – Salt and black pepper.

MAKE THE LAMB FILLING: First, in a large frying pan over medium-high heat, add oil and heat for 2 minutes. Place onion and cook for 4 minutes while stirring occasionally.

MAKE THE LAMB FILLING: Next, add carrots (or frozen peas and carrots), garlic, rosemary, and parsley, and saute for 2-3 minutes on medium heat. Add the tender chunks of lamb, salt, black pepper, and Worcestershire sauce. Stir to combine and cook for a couple of minutes.

MAKE THE LAMB FILLING: Then, add flour and tomato paste. Stir until well combined. Add the broth and bring it to a boil, then reduce to simmer for 5 minutes. After that, set the lamb mixture aside. Preheat the oven to 400 degrees F.

MAKE THE POTATO TOPPING: Add peeled and cut potatoes to a large pot. Cover the potatoes with hot water. Cook potatoes until they are fork tender, about 12–15 minutes. Then, drain the potatoes and add them to a large bowl.

MAKE THE POTATO TOPPING: Now, Mash the potatoes a little, and then add heavy cream, egg, parmesan cheese, salt, black pepper, and butter. Mash them again and stir until all the ingredients are mixed.

ASSEMBLE THE PIE: After that, pour the lamb mixture into a 10-inch cast iron skillet or 9x9 baking dish. Spread the mixture into an even layer. Add mashed potatoes on top of the lamb mixture. Carefully spread the mashed potatoes into an even layer. Drizzle melted butter over the top.

ASSEMBLE THE PIE: Finally, bake uncovered for 20 minutes and broil until lightly golden. Cool for 10 minutes before serving.