Preheat your oven to 350° F (180° C).
Heat a large pan over medium-high heat and add a dash of oil.
Add the ground lamb, spreading it evenly, and cook until browned.
Break apart the lamb with a wooden spoon as it browns, then season it with salt and pepper.
Add the chopped onion, minced garlic, and diced carrots to the pan.
Cook the vegetables for 2-4 minutes until softened.
Stir in the tomato paste, Worcestershire sauce, thyme, and rosemary.
Pour in the chicken broth, stirring to combine, and let it simmer for about 5 minutes.
Spread the lamb mixture evenly in a baking dish.
Prepare the mashed potatoes by boiling them until tender, then mash with butter, cream, and a bit of salt.
Top the lamb mixture with the mashed potatoes, spreading evenly.
Bake in the preheated oven for 20-25 minutes until the top is golden brown.
Let it cool slightly before serving.