Preparation Steps

• Preheat the oven to 375°F (190°C).
• In a large skillet over medium heat, warm the olive oil. Add the onion, carrots, and celery. Cook for 5–7 minutes until softened. Stir in the garlic and cook for another minute.
• Add the ground lamb (or beef) to the skillet. Cook, breaking it up with a spoon, until browned and no longer pink, about 8–10 minutes. Drain excess fat if needed.
• Stir in the thyme, rosemary, Worcestershire sauce, frozen peas, drained tomatoes, and broth. Season with salt and pepper. Bring to a simmer and cook for 10–15 minutes until the mixture thickens slightly. Remove from heat and set aside.
• While the filling cooks, place the cubed potatoes in a pot of salted water. Bring to a boil and cook for 15–20 minutes until tender. Drain well and return to the pot.
• Add the milk, butter, and nutmeg (if using) to the potatoes. Mash until smooth and creamy. Season with salt and pepper to taste.
• Transfer the meat filling to a 9x13-inch baking dish. Spread the mashed potatoes evenly over the top. Use a fork to create ridges on the surface for browning.
• Sprinkle shredded cheddar cheese over the mashed potatoes if desired. Bake for 25–30 minutes until the top is golden and the filling is bubbling.
• Let cool for 5–10 minutes before serving. Enjoy warm!