01 - Preheat oven to 400°F.
02 - Cook the potatoes in a large pot of salted boiling water for 15–20 minutes until tender. Drain and mash with butter, milk, salt, and pepper. Stir in cheddar cheese if using. Set aside.
03 - While the potatoes cook, heat olive oil in a large skillet over medium heat. Add onion and carrot; sauté for 4–5 minutes until softened.
04 - Add garlic and cook for 1 minute until fragrant.
05 - Add ground beef or lamb, breaking it up with a spoon, and cook until browned. Drain excess fat if needed.
06 - Stir in tomato paste, Worcestershire sauce, thyme, salt, and pepper until well combined.
07 - Add broth and peas. Simmer for 5 minutes until slightly thickened. Remove from heat.
08 - Divide the meat filling evenly among six lightly greased ramekins or muffin tin wells.
09 - Spoon or pipe the mashed potatoes on top of each, spreading to cover the filling completely.
10 - Place ramekins on a baking sheet and bake for 20 minutes, or until the tops are golden and the filling bubbles at the edges.
11 - Cool for 5 minutes before serving.