Ingredients:

  • 2 large Yellow Onions, thinly sliced
  • 4 Tbsp Unsalted Butter, divided
  • 5 lbs Russet Potatoes, peeled and quartered
  • 1/2 cup Whole Milk, warmed
  • 2 Tbsp Crème Fraîche (or Sour Cream)
  • 1/2 cup Sharp Cheddar Cheese, grated, for topping
  • Kosher Salt & Fresh Black Pepper, To taste
  • 2 Tbsp Olive Oil
  • 5 lbs Ground Lamb (at least 15% fat content)
  • 1 medium Yellow Onion, diced finely
  • 2 medium Carrots, diced finely
  • 2 stalks Celery, diced finely
  • 3 cloves Garlic, minced
  • 1 Tbsp All-Purpose Flour
  • 2 Tbsp Tomato Purée (or Paste)
  • 1 Tbsp Balsamic Vinegar
  • 1/2 cup Dry Red Wine (Optional)
  • 5 cups Beef or Lamb Stock, low-sodium preferred
  • 1 Tbsp Worcestershire Sauce
  • 1 Tbsp Fresh Rosemary, finely chopped
  • 1 tsp Fresh Thyme, leaves only
  • 1 Bay Leaf

Instructions:

  1. Caramelize the Onions: In a separate pan, melt 2 Tbsp of butter. Add the sliced onions with a pinch of salt. Cook over low heat for 30–40 minutes, stirring occasionally, until deeply golden brown and sweet. Set aside.
  2. Cook the Potatoes: Place peeled potatoes in a large pot, cover with salted cold water, and bring to a boil. Cook until fork-tender (about 15-20 minutes). Drain thoroughly and allow the potatoes to steam dry for 5 minutes.
  3. Prepare the Mash: While still hot, mash or rice the potatoes. Gently mix in the remaining 2 Tbsp butter, warm milk, and crème fraîche until just combined. Season generously with salt and pepper.
  4. Fold In: Gently fold in half of the caramelized onions into the mash. Reserve the remaining caramelized onions for topping the filling.
  5. Brown the Lamb: Heat olive oil in a Dutch oven over medium-high heat. Add the ground lamb and brown aggressively, breaking it up. Drain excess fat. Set the lamb aside.
  6. Sauté the Mirepoix: Reduce heat to medium. Add the diced onion, carrots, and celery. Cook gently for 8–10 minutes until softened and translucent. Add the garlic and cook for 1 minute more.
  7. Build the Gravy Base: Stir in the flour and tomato purée; cook for 1 minute to toast the flour. Deglaze the pan with balsamic vinegar and optional red wine, scraping up any browned bits. Allow the liquid to reduce by half.
  8. Simmer and Reduce: Return the lamb to the pot. Add the stock, Worcestershire sauce, rosemary, thyme, bay leaf, salt, and pepper. Bring to a gentle simmer, then reduce heat to low. Cook uncovered for 25–30 minutes, or until the sauce is thick. Remove the bay leaf before assembling.
  9. Layer the Filling: Pour the hot lamb filling evenly into a 9x13 inch baking dish. Spread the reserved caramelized onions over the top of the filling.
  10. Top with Mash: Spoon the mash evenly over the filling, ensuring the filling is completely sealed. Score the mash lightly with a fork to create peaks.
  11. Crust & Finish: Sprinkle the grated sharp cheddar cheese evenly over the top.
  12. Bake: Place the pie in a preheated oven at 375°F (190°C) for 35–40 minutes, or until the filling is bubbling vigorously and the mash topping is deeply golden and crusty.
  13. Rest: Remove from the oven and let the pie rest for 10 minutes before serving. This allows the gravy to stabilize.