Quick Recipe Version (TL;DR)
Quick Ingredients
- 2 1/2 lb Yukon Gold potatoes, peeled and cut into 1 1/2-inch chunks
- 6 tbsp unsalted butter, divided
- 3/4 cup whole milk, warmed
- 1/4 cup sour cream
- 2 tsp kosher salt, divided, plus more to taste
- 1/2 tsp black pepper, plus more to taste
- 1 tbsp olive oil
- 1 1/2 lb ground lamb (shepherd’s pie) or ground beef (cottage pie)
- 1 medium yellow onion, diced
- 2 medium carrots, diced (about 1 cup)
- 2 cloves garlic, minced
- 2 tbsp tomato paste
- 2 tbsp all-purpose flour
- 2 cups low-sodium beef broth
- 1 tbsp Worcestershire sauce
- 1 tsp dried thyme
- 1/2 tsp kosher salt (for filling), plus more to taste
- 1 cup frozen peas
Do This
- 1) Heat oven to 400°F. Butter a 9×13-inch (3-quart) baking dish.
- 2) Boil potatoes in salted water until very tender, 12–15 minutes. Mash with butter, warm milk, sour cream, salt, and pepper.
- 3) Brown lamb or beef in oil. Add onion and carrots; cook until softened. Add garlic and tomato paste.
- 4) Stir in flour, then broth, Worcestershire, thyme, salt, and pepper. Simmer until thick and glossy. Stir in peas.
- 5) Spread filling in dish. Dollop mashed potatoes on top, spread to the edges, and rake with a fork.
- 6) Bake 25–30 minutes until bubbling and browned. Optional: broil 2–3 minutes for deeper color.
- 7) Rest 10 minutes, then spoon and serve.
Why You’ll Love This Recipe
- Comfort-food classic: rich, savory gravy and a fluffy potato lid with golden peaks.
- Weeknight-friendly: straightforward steps and everyday ingredients.
- Great for leftovers: reheats beautifully and slices into tidy portions.
- Flexible: make it with lamb (traditional shepherd’s pie) or beef (cottage pie).
Grocery List
- Produce: Yukon Gold potatoes (2 1/2 lb), yellow onion (1), carrots (2), garlic (2 cloves)
- Dairy: unsalted butter, whole milk, sour cream
- Meat: ground lamb or ground beef (1 1/2 lb)
- Frozen: peas (1 cup)
- Pantry: olive oil, tomato paste, all-purpose flour, low-sodium beef broth, Worcestershire sauce, dried thyme, kosher salt, black pepper
Full Ingredients
Mashed Potato Topping
- 2 1/2 lb Yukon Gold potatoes, peeled and cut into 1 1/2-inch chunks
- 1 1/2 tbsp kosher salt (for the potato water)
- 5 tbsp unsalted butter
- 3/4 cup whole milk, warmed
- 1/4 cup sour cream
- 1/2 tsp kosher salt (for seasoning the mash), plus more to taste
- 1/2 tsp black pepper, plus more to taste
Meat & Vegetable Filling (Rich Gravy)
- 1 tbsp olive oil
- 1 1/2 lb ground lamb (traditional shepherd’s pie) or ground beef (cottage pie)
- 1 medium yellow onion, diced (about 1 1/2 cups)
- 2 medium carrots, diced small (about 1 cup)
- 1/2 tsp kosher salt (for vegetables and meat), plus more to taste
- 1/2 tsp black pepper, plus more to taste
- 2 cloves garlic, minced
- 2 tbsp tomato paste
- 2 tbsp all-purpose flour
- 2 cups low-sodium beef broth
- 1 tbsp Worcestershire sauce
- 1 tsp dried thyme
- 1 cup frozen peas
For the Baking Dish
- 1 tbsp unsalted butter (to grease the dish)
- 1 tbsp unsalted butter (optional, to dot on top for extra browning)
Step-by-Step Instructions
Step 1: Prep the oven and baking dish
Arrange a rack in the upper-middle of the oven and preheat to 400°F.
Butter a 9×13-inch (3-quart) baking dish with 1 tbsp butter. Set aside.
Step 2: Boil the potatoes until very tender
Add the potatoes to a large pot and cover with cold water by about 1 inch. Stir in 1 1/2 tbsp kosher salt.
Bring to a boil over high heat, then reduce to a steady simmer. Cook until the potatoes are very tender and a knife slips in easily, 12–15 minutes.
Drain well, then return the potatoes to the hot pot for 1 minute, shaking the pot gently to help moisture evaporate (this makes fluffier mash).
Step 3: Mash the potatoes until fluffy and creamy
Off the heat, add 5 tbsp butter to the hot potatoes and let it melt for about 30 seconds.
Mash with a potato masher until mostly smooth. Pour in the 3/4 cup warmed milk, add 1/4 cup sour cream, 1/2 tsp kosher salt, and 1/2 tsp black pepper. Mash until fluffy and cohesive.
Taste and adjust salt and pepper if needed. Set the mash aside (cover the pot to keep it warm).
Step 4: Brown the meat for deep savory flavor
Heat a large skillet (12-inch works well) over medium-high heat. Add 1 tbsp olive oil, then add the 1 1/2 lb ground lamb or beef.
Cook, breaking it up with a spoon, until browned with some deeper caramelized bits, 7–9 minutes. If there is excess fat (more than about 2 tbsp), carefully spoon some off.
Step 5: Build the gravy with onions, carrots, and Worcestershire-thyme vibes
Add the diced onion and carrots to the skillet. Season with 1/2 tsp kosher salt and 1/2 tsp black pepper. Cook, stirring occasionally, until the onion softens and the carrots start to lose their raw crunch, 6–8 minutes.
Add the minced garlic and cook 30 seconds until fragrant. Stir in the 2 tbsp tomato paste and cook for 1 minute to deepen its flavor.
Sprinkle in the 2 tbsp flour and stir constantly for 1 minute to coat everything.
Slowly pour in the 2 cups beef broth, stirring as you go to prevent lumps. Stir in 1 tbsp Worcestershire sauce and 1 tsp dried thyme.
Bring to a simmer and cook until the gravy is thick, glossy, and coats the spoon, 5–7 minutes. Stir in the 1 cup frozen peas and simmer 1 minute. Taste and adjust seasoning.
Step 6: Assemble the casserole (seal it edge-to-edge)
Spoon the hot filling into the buttered baking dish and spread into an even layer.
Dollop the mashed potatoes over the top in large spoonfuls, then gently spread to the edges so the potatoes touch the sides of the dish. This “seal” helps keep the gravy bubbling under the crust instead of drying out.
Use a fork to rake the surface into ridges (more ridges = more browned peaks). For extra browning, dot the top with 1 tbsp butter (optional).
Step 7: Bake until bubbling and beautifully browned
Bake at 400°F until the edges are bubbling and the potato topping is browned on top, 25–30 minutes.
If you want a deeper, toastier crust, switch the oven to broil on high and broil for 2–3 minutes, watching closely to avoid scorching.
Step 8: Rest, then serve for clean scoops and better flavor
Let the casserole rest for 10 minutes before serving. This helps the gravy thicken slightly so each spoonful holds together.
Spoon into bowls (or cut into squares if you want neater portions) and serve hot.
Pro Tips
- Dry the potatoes before mashing: letting them steam in the hot pot for 1 minute prevents watery mash.
- Thicken the gravy properly: cook the flour for 1 minute, then simmer the broth mixture until it coats a spoon (5–7 minutes). This keeps the filling rich, not soupy.
- Seal the edges with potatoes: spreading mash to the dish edges helps trap moisture and creates that classic spoon-through crust.
- Fork ridges = better browning: textured peaks brown faster and look beautiful.
- Let it rest: 10 minutes makes serving cleaner and keeps tongues safer from molten gravy.
Variations
- Extra-veg version: add 1 cup diced mushrooms with the onions, or stir 1 cup frozen corn in with the peas.
- Cheddar topping: mix 1 cup (4 oz) shredded sharp cheddar into the mashed potatoes for a richer, more golden crust.
- Guinness-style gravy: replace 1/2 cup of the beef broth with 1/2 cup stout beer; simmer 1 extra minute to cook off the harsh alcohol edge.
Storage & Make-Ahead
Refrigerate: Cool completely, cover tightly, and refrigerate for up to 4 days.
Reheat: Reheat individual portions in the microwave in 60–90 second bursts until hot, or reheat the whole dish covered with foil in a 350°F oven for 25–35 minutes, uncovering for the last 10 minutes to re-crisp the top.
Make-ahead: Assemble the casserole completely, cool, cover, and refrigerate up to 24 hours before baking. Bake straight from the fridge at 400°F for 35–40 minutes (it takes longer when cold), then broil 2–3 minutes if desired.
Freeze: Cool completely, wrap tightly (plastic wrap plus foil), and freeze up to 2 months. Thaw in the fridge for 24 hours before baking at 400°F for 35–45 minutes, or until the center reaches 165°F.
Nutrition (per serving)
Approximate, based on 6 servings: 520 calories, 29 g protein, 50 g carbohydrates, 23 g fat, 9 g saturated fat, 5 g fiber, 8 g sugars, 780 mg sodium.
