Preheat your oven to 400°F (200°C).
In a large skillet, brown the ground lamb or beef over medium heat.
Add chopped onion and carrots, cooking until softened.
Stir in garlic and cook for another minute.
Add tomato paste, Worcestershire sauce, and beef broth.
Mix in frozen peas, and season with salt and pepper.
Simmer the mixture for about 15 minutes until thickened.
Spread the meat mixture evenly in a baking dish.
Top with a layer of mashed potatoes, smoothing it out.
Sprinkle shredded cheddar cheese on top.
Bake in the oven for 20-25 minutes until golden brown.