In a large skillet, brown the ground lamb (or beef) over medium heat until fully cooked. Drain any excess fat.
Add the chopped onion and diced carrots to the skillet. Cook until the onion is translucent, about 5 minutes. Stir in the minced garlic and cook for an additional minute.
Mix in the tomato paste, Worcestershire sauce, and dried thyme. Stir well to combine.
Pour in the beef broth and let the mixture simmer for about 10 minutes. Add the frozen peas and season with salt and pepper to taste.
While the meat mixture simmers, prepare your mashed potatoes if you haven’t done so already. Make sure they are creamy and well-seasoned.
In a baking dish, spread the meat mixture evenly across the bottom. Top it with the mashed potatoes, spreading them out to cover completely.
If desired, sprinkle shredded cheddar cheese over the mashed potatoes for added flavor and richness.
Place the dish in the preheated oven and bake for 30-40 minutes, or until the top is golden and the filling is bubbly.
Once done, let the Shepherd’s Pie cool for a few minutes. Garnish with fresh parsley before serving.