Preheat the oven to 400°F (200°C). Pierce the potatoes with a fork and place them on a baking sheet. Bake for 45 minutes or until tender.

In a skillet over medium heat, cook the ground lamb or beef until browned. Drain excess fat.

Add the diced onion, garlic, and carrots to the skillet. Cook until the vegetables are softened, about 5-7 minutes.

Stir in the tomato paste, beef broth, Worcestershire sauce, thyme, salt, and pepper. Simmer for 10 minutes.

Add the frozen peas and cook for an additional 2 minutes. Remove from heat.

In a mixing bowl, scoop out the insides of the baked potatoes, leaving a thin layer of potato in the skin.

Mash the potato flesh with milk, butter, salt, and pepper until smooth and creamy.

Spoon the meat filling into each potato skin, then top with the mashed potatoes. Sprinkle with cheddar cheese if desired.

Return to the oven and bake for an additional 15 minutes, or until the tops are golden brown.