Ingredients:

  • 1.5 lb (680 g) ground lamb (lean to medium fat)
  • 1 tbsp (15 ml) olive oil (if lamb is very lean) or 1 tbsp (14 g) unsalted butter
  • 1 large yellow onion, finely diced (about 150 g)
  • 2 medium carrots, peeled and diced (about 120 g)
  • 2 celery stalks, diced (about 100 g)
  • 2 cloves garlic, minced
  • 2 tbsp (30 g) tomato paste
  • 2 tbsp (16 g) all-purpose flour
  • 1 cup (240 ml) beef or lamb stock (low-sodium preferred)
  • 1 tbsp (15 ml) Worcestershire sauce
  • 1 cup (150 g) frozen peas, thawed
  • 2 tsp fresh thyme leaves or 1/2 tsp dried thyme
  • 1 bay leaf
  • Salt and freshly ground black pepper, to taste
  • 2 lb (900 g) Yukon Gold or floury potatoes, peeled and cut into uniform chunks
  • 4 tbsp (60 g) unsalted butter
  • 1/2 cup (120 ml) whole milk or single cream (or mix of milk + cream), warmed
  • Optional: 1 egg yolk (for extra gloss and stability)
  • Salt and white or black pepper, to taste (for potatoes)
  • Optional topping: 1/2 cup (50 g) grated mature cheddar or Parmesan for browning
  • Garnish (optional): Fresh parsley or extra thyme leaves, chopped
  • Garnish (optional): A drizzle of extra-virgin olive oil or a knob of butter before serving

Instructions:

  1. Prep vegetables and potatoes: peel and chop potatoes into even chunks; dice onion, carrots, celery; mince garlic.
  2. Cook potatoes: place potatoes in cold salted water; bring to a boil and simmer until fork-tender, about 12–15 minutes. Drain well and return to hot pot to steam off excess moisture.
  3. Brown the lamb and soften aromatics: heat oil or butter in a skillet over medium-high heat. Add ground lamb, break up, and cook until browned and most moisture evaporates. Remove excess fat leaving about 1 tbsp for flavor. Add onion, carrots and celery; sauté 6–8 minutes until softened and beginning to color. Add garlic and cook 30–60 seconds.
  4. Build and thicken the ragu: stir in tomato paste and cook 1–2 minutes. Sprinkle flour over mixture and cook 1 minute. Gradually add stock while scraping up browned bits. Add Worcestershire sauce, thyme and bay leaf. Simmer uncovered 12–15 minutes until sauce reduces and thickens. Remove bay leaf; stir in peas and adjust seasoning. Filling should cling to a spoon and not be soupy.
  5. Make the mashed potatoes: drain and rice or mash potatoes until smooth. Fold in butter and warmed milk in stages until creamy and spreadable. Optionally beat in an egg yolk off-heat for richness. Season with salt and pepper; potatoes should hold a soft peak and be glossy, not runny.
  6. Assemble: spoon the lamb filling into an ovenproof skillet or transfer to a 9×13-inch casserole. Smooth or pipe the mashed potatoes over the filling, sealing to the edges to prevent bubbling. Use a fork to create ridges and sprinkle grated cheese if using.
  7. Bake: preheat oven to 400°F (200°C). Bake 20–25 minutes until potatoes are golden and filling bubbles at the edges. For extra browning, broil 2–3 minutes while watching closely.
  8. Rest and serve: let rest 10 minutes to set before portioning. Garnish with chopped parsley or thyme and a drizzle of olive oil or knob of butter. Reheat leftovers to 165°F (74°C) before serving.