Make the Mashed Potatoes

Place the potatoes in a large pot and fill with cold water and a generous sprinkling of salt. Place over a medium-high flame and partially cover. Once the water comes to a boil, cook for about 20 to 25 minutes, reducing the heat if necessary, or until the potatoes fall easily crumble when poked with a fork. Drain the water and return the potatoes to the pot. Add the butter, ¼ cup cream, the cheddar cheese, and a sprinkling of garlic salt. Using a hand mixer or potato mashers, blend the potatoes until smooth. Add additional cream as needed to create a smooth consistency. Taste and add additional garlic salt as desired. Set aside.

Make the Filling

Heat a large saucepan over medium heat and lightly spray with nonstick spray. When hot, work in batches to sear the lamb shoulder chunks, ensuring that you do not cook the meat through (you’re looking for a very light brown on all sides and then immediately remove the meat from the pan). Repeat with the remaining chunks of lamb and set aside in a bowl.

Add the onions, stirring immediately to scrape up any browned bits. Cook for about 3 minutes until just starting to brown. Add the ground lamb and cook until browned through, breaking up the meat with a wooden spoon. Add the garlic cloves and tomato paste, stirring to thoroughly combine the tomato paste with the meat and onions. Sprinkle the top with flour and stir to fully saturate the flour. Slowly pour in the beef broth, stirring constantly. Add the Worcestershire sauce and steak sauce. Bring to a light simmer and return the lamb chunk back to the pan with any liquids. Stir to combine and season to taste with salt and pepper.

Let simmer on low while you preheat the oven to 400°F.

Bake

In a baking dish about 9” x 13”, layer the peas and carrots on the bottom. Add the fresh thyme to the saucepan and stir to combine. Pour the lamb and gravy over the top of the peas and carrots. Dollop the mashed potatoes over the top of the lamb and gravy, using the back of a spoon to smooth over the top.

Place the baking dish on the middle rack with either aluminum foil or a baking sheet on a rack below to catch any drippings. Bake for 30 to 40 minutes, or until the sauce is bubbling and the top is golden brown.

Serve immediately. Enjoy!