Shepherd's Pie (lamb) Recipe

Prep vegetables

Heat a large ovenproof skillet or sauté pan over medium heat. Add olive oil and 1 tablespoon butter. When butter melts and foams, add the diced onion, carrots and celery. Cook, stirring occasionally, until softened and beginning to brown, about 6–8 minutes. Add the minced garlic and cook 30 seconds until fragrant.

Brown lamb

Increase heat to medium-high and add the ground lamb. Break it up with a spoon and cook until no longer pink and beginning to brown, about 6–8 minutes. Season with 3/4 tsp of the salt and 1/4 tsp of the pepper as it cooks.

Build sauce

Stir in the tomato paste and cook 1–2 minutes to caramelize. Pour in the red wine (or 1/2 cup stock if not using wine) to deglaze the pan, scraping up browned bits from the bottom. Let the wine reduce by half, about 2–3 minutes. Add the remaining stock, Worcestershire sauce, thyme, and rosemary. Bring to a simmer.

Thicken and finish filling

Mix the cornstarch (or flour) with a tablespoon of cold water to make a slurry and stir into the simmering mixture to thicken slightly. Simmer gently 4–6 minutes until the sauce is glossy and coats the back of a spoon. Stir in the thawed peas and adjust seasoning with remaining salt and pepper to taste. Remove from heat and set aside while you make the mashed potato topping.

Cook potatoes

Place the potato cubes in a pot and cover with cold water by 1 inch. Add a pinch of salt and bring to a boil over high heat. Reduce to a simmer and cook until potatoes are fork-tender, 12–15 minutes. Drain well in a colander.

Mash

Return drained potatoes to the hot pot so residual heat evaporates excess moisture for 1 minute. Add 2 tablespoons butter, warmed milk, sour cream (if using), and the remaining 3/4 tsp salt and 1/4 tsp pepper. Mash with a potato masher or ricer until smooth but still slightly textured. Taste and adjust seasoning.

Finish topping

If desired, beat the egg yolk and brush lightly over the top of the mashed potatoes before baking for color, or fold in the grated cheese for a richer top. Keep mashed potatoes warm.

Preheat the oven to 400°F (200°C) if not already using an ovenproof pan. If your skillet is ovenproof, you can assemble in it; otherwise transfer the lamb mixture to a 9x9-inch (or similar) baking dish and spread into an even layer.

Using a spoon or spatula, spread the mashed potatoes over the lamb in an even layer, taking care to seal the edges so the filling doesn't bubble up. Use a fork to create shallow ridges on the surface to encourage browning.

If using, sprinkle the grated cheese over the top or brush mashed potatoes with the beaten egg yolk for a golden finish.

Bake in the preheated oven until the top is golden and filling is bubbling around the edges, 20–25 minutes. For extra browning, place under the broiler 1–2 minutes — watch carefully to prevent burning.

Remove from oven and let rest 5–10 minutes. Sprinkle chopped parsley over the top before serving.