Quick Recipe Version (TL;DR)
Quick Ingredients
- 2 lb (900 g) Yukon Gold potatoes, peeled and chunked
- 6 tbsp (85 g) unsalted butter
- 1/2 cup (120 ml) whole milk, warmed
- 1/4 cup (60 g) sour cream
- 1 large egg yolk (optional)
- 1.5 lb (680 g) ground lamb
- 1 tbsp olive oil
- 1 medium yellow onion, finely chopped
- 2 medium carrots, 1/4-inch dice
- 3 garlic cloves, minced
- 2 tsp finely chopped fresh rosemary; 1 tsp fresh thyme
- 2 tbsp tomato paste
- 2 tbsp all-purpose flour
- 1/2 cup (120 ml) dry red wine (optional)
- 1 cup (240 ml) beef or lamb stock
- 1 cup (140 g) frozen peas, thawed
- Kosher salt and black pepper
Do This
- 1. Heat oven to 400°F (200°C). Butter a 2 to 2.5-qt baking dish.
- 2. Boil potatoes in salted water until tender, 15–18 minutes; drain.
- 3. Mash with butter, warm milk, sour cream, salt, pepper; beat in yolk.
- 4. Brown lamb in oil, 6–8 minutes; drain excess fat.
- 5. Sauté onion and carrots; add garlic, herbs, tomato paste; stir in flour.
- 6. Deglaze with wine; add stock and Worcestershire; simmer to thicken; fold in peas.
- 7. Fill dish, top with mash, rough up peaks; bake 20–25 minutes until bubbly and browned.
Why You’ll Love This Recipe
- Classic comfort: buttery mashed potatoes crowning a rich, savory lamb filling.
- Weeknight-friendly technique with make-ahead and freezer options.
- Balanced flavors: rosemary, thyme, tomato paste, and Worcestershire for depth.
- Crispy golden peaks meet a saucy, vegetable-studded interior.
Grocery List
- Produce: Yukon Gold potatoes, yellow onion, carrots, garlic, fresh rosemary, fresh thyme
- Dairy: unsalted butter, whole milk, sour cream, 1 egg (optional)
- Pantry: ground lamb, olive oil, tomato paste, all-purpose flour, Worcestershire sauce, dry red wine (optional), beef or lamb stock, frozen peas, kosher salt, black pepper
Full Ingredients
Potato Topping
- 2 lb (900 g) Yukon Gold potatoes, peeled and cut into 1.5-inch chunks
- 6 tbsp (85 g) unsalted butter
- 1/2 cup (120 ml) whole milk, warmed
- 1/4 cup (60 g) sour cream
- 1 large egg yolk, optional (for extra browning and structure)
- 1 tsp kosher salt (plus more to taste)
- 1/2 tsp freshly ground black pepper
Lamb Filling
- 1 tbsp olive oil
- 1.5 lb (680 g) ground lamb
- 1 medium yellow onion, finely chopped
- 2 medium carrots, 1/4-inch dice
- 3 garlic cloves, minced
- 2 tsp finely chopped fresh rosemary
- 1 tsp fresh thyme leaves (or 1/2 tsp dried)
- 2 tbsp tomato paste
- 2 tbsp all-purpose flour
- 1/2 cup (120 ml) dry red wine, optional
- 1 cup (240 ml) beef or lamb stock, plus a splash more as needed
- 1 tbsp Worcestershire sauce
- 1 tsp kosher salt, or to taste
- 1/2 tsp freshly ground black pepper
- 1 cup (140 g) frozen peas, thawed
Step-by-Step Instructions
Step 1: Preheat and prepare your dish
Heat oven to 400°F (200°C). Lightly butter or spray a 2 to 2.5-quart baking dish (an 11×7-inch or 9-inch square works well). Set a large pot of well-salted water on the stove for the potatoes.
Step 2: Cook the potatoes
Add the potato chunks to the pot, bring to a boil, then simmer until very tender when pierced with a knife, 15–18 minutes. Drain thoroughly, then return potatoes to the hot pot off the heat for 1 minute to let excess moisture steam off.
Step 3: Mash the topping
Add the butter, warm milk, sour cream, 1 tsp salt, and 1/2 tsp pepper to the potatoes. Mash until smooth and fluffy. If using, beat in the egg yolk for extra richness and browning. Taste and adjust seasoning. Keep warm.
Step 4: Brown the lamb
Meanwhile, heat the olive oil in a large skillet (12-inch) over medium-high heat. Add the ground lamb and cook, breaking it up with a spoon, until deeply browned with crispy bits, 6–8 minutes. Spoon off excess fat, leaving about 1 tablespoon in the pan. Season with a pinch of salt and pepper.
Step 5: Build the savory sauce
Add the onion and carrots to the lamb and cook, stirring, until the vegetables soften, 5–6 minutes. Stir in the garlic, rosemary, and thyme; cook 1 minute until fragrant. Add the tomato paste and cook, stirring, until it darkens slightly, about 1 minute. Sprinkle in the flour and cook 1 minute to remove the raw taste. Deglaze with the red wine (if using), scraping up browned bits; let it reduce by half, 1–2 minutes. Stir in the stock and Worcestershire and simmer 3–5 minutes, until thick, glossy, and spoon-coating. Taste and season with the remaining salt and pepper. Fold in the peas and remove from heat.
Step 6: Assemble the pie
Spoon the lamb mixture into the prepared baking dish, spreading in an even layer. Dollop the mashed potatoes over the top, then gently spread to the edges to seal. Use a fork to create ridges and peaks for extra browning. If you like, dot with a little extra butter.
Step 7: Bake to bubbly perfection
Bake at 400°F (200°C) until the filling bubbles at the edges and the potato peaks are golden, 20–25 minutes. For deeper color, broil for 1–2 minutes, watching closely.
Step 8: Rest and serve
Let the pie rest 10 minutes to set for cleaner slices. Sprinkle with a few rosemary leaves or cracked black pepper if desired, and serve warm.
Pro Tips
- Start potatoes in cold, salted water for even cooking and better texture.
- Warm milk prevents gummy mash and helps the butter emulsify smoothly.
- Darken the tomato paste in the pan; that quick caramelization adds big flavor.
- Seal the mash to the dish edges so the filling doesn’t bubble up over the top.
- Rough up the potato surface with a fork—those ridges brown into delicious, crispy peaks.
Variations
- Cottage Pie: Swap ground lamb for ground beef; everything else stays the same.
- Sweet Potato Top: Use 2 lb (900 g) sweet potatoes for a subtly sweet, orange-topped pie.
- Gluten-Free: Skip the flour and thicken with 1 tbsp cornstarch mixed with 2 tbsp cool stock; stir into the simmering filling.
Storage & Make-Ahead
Assemble up to 24 hours ahead, cover, and refrigerate; add 10 minutes to the bake time. Leftovers keep 3–4 days in the fridge; reheat at 350°F (175°C) for 20–25 minutes or microwave gently, then broil briefly for a crisp top. To freeze, assemble but do not bake; wrap well and freeze up to 2 months. Bake from thawed at 400°F (200°C) for 30–35 minutes, or from frozen at 375°F (190°C) for 50–60 minutes, until hot and bubbling.
Nutrition (per serving)
Approx. 610 calories; 25 g protein; 37 g fat; 38 g carbohydrates; 4 g fiber; 940 mg sodium. Values are estimates and will vary based on brands and exact ingredients.
