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