Heat olive oil in a large skillet over medium-high heat.
Add ground lamb, breaking it apart as it browns.
Sprinkle with salt and pepper for flavor.
Add the chopped onion, diced carrots, and minced garlic to the skillet.
Cook them together until the vegetables are tender, usually 2-4 minutes.
Stir in the tomato paste, letting it cook with the mixture for a minute.
Pour in beef broth and Worcestershire sauce.
Let it simmer until the sauce thickens.
Mix in rosemary and thyme.
Let the flavors blend for about 5 minutes.
Transfer the mixture to a baking dish.
Spread the mashed potatoes on top, ensuring even distribution.
Sprinkle grated Parmesan over the potatoes.
Bake in a preheated oven at 400°F for 20 minutes, or until the top is golden brown.