POTATOES: Boil the potatoes in a large pot of salted water until fork-tender. Sometimes I throw in a couple of garlic cloves with the potatoes. Drain, mash, and mix in the remaining mashed potato ingredients. Season with salt and pepper to taste.

BEEF FILLING: Heat a large oven-safe pot over medium-high heat. Add the ground lamb and crumble the meat using a wooden spoon. Cook for 4-5 minutes until the meat browns. Drain any excess grease, leaving just a tiny bit. Add the oil and mirepoix, season the veggies with a pinch of salt, and cook until translucent, about 7-9 minutes. Add the garlic and cook for another 30 seconds or until fragrant.

GRAVY: Preheat the oven to 425°F. Sprinkle the ground meat mixture with cinnamon, nutmeg, and cornstarch. Stir to combine and cook for 15 seconds. Add the Worcestershire sauce, tomato paste, herbs, bay leaf, and beef stock. Bring the gravy to a simmer, then reduce the heat to low and let it simmer for 15 minutes. Remove the herbs, stir in the peas, and adjust with salt and pepper as needed.

BAKE: Drop large dollops of the prepared mashed potatoes on top of the beef gravy and gently smooth them out. Bake for 15 minutes, then finish under the broiler if you want a golden brown top. Let cool for several minutes before serving.