Place the potatoes in a large pot and cover with cold water. Bring to a boil, then simmer for 15-20 minutes or until tender. Drain and mash with butter, milk, salt, and pepper until smooth. Set aside.

Preheat your oven to 400°F (200°C). Heat olive oil in a large skillet over medium heat. Add onion, garlic, and carrot, and sauté until softened, about 5 minutes.

Add the ground lamb (or beef) to the skillet, breaking it up with a spoon, and cook until browned. Season with salt and pepper, then stir in the tomato paste, Worcestershire sauce, beef broth, thyme, and rosemary. Bring to a simmer, and cook for 10-15 minutes, until the mixture has thickened. Stir in the peas.

Transfer the meat and vegetable mixture to a baking dish. Spoon the mashed potatoes on top, spreading them evenly to cover the filling. For a golden finish, use a fork to create texture on the surface.

Bake in the preheated oven for 20 minutes, or until the top is lightly browned and the filling is bubbling.

Let the shepherd’s pie cool for a few minutes before serving. Enjoy warm!