Quick Recipe Version (TL;DR)
Quick Ingredients
- 2.5 lb russet potatoes, peeled and cubed
- 4 tbsp unsalted butter + 1 tbsp for skillet
- 1.5 cups (6 oz) sharp cheddar, grated + 1/2 cup for topping
- 1/2 cup sour cream; 1/2 cup warm milk; 1 egg yolk
- 2 tbsp olive oil
- 1 large onion; 2 carrots; 2 celery ribs, all finely diced
- 12 oz cremini mushrooms, sliced
- 4 garlic cloves, minced
- 1.5 lb 85% lean ground beef
- 2 tbsp tomato paste; 2 tbsp all-purpose flour
- 1 cup stout beer; 1 cup beef broth
- 2 tbsp Worcestershire; 1 tbsp fresh thyme (or 1 tsp dried); 2 bay leaves
- 1 cup frozen peas; kosher salt and black pepper
Do This
- 1. Heat oven to 400°F (200°C). Boil potatoes in salted water until tender, 12–15 minutes.
- 2. Brown mushrooms in oil and 1 tbsp butter; set aside.
- 3. Sauté onion, carrot, celery; add garlic. Brown beef. Stir in tomato paste.
- 4. Sprinkle flour, cook 1 minute. Add stout, broth, Worcestershire, thyme, bay, and mushrooms; simmer 15–20 minutes. Stir in peas.
- 5. Drain potatoes; mash with 4 tbsp butter, cheddar, sour cream, warm milk, yolk, salt, and pepper.
- 6. Fill a 9×13-inch dish; top with mash, rough up with a fork; sprinkle extra cheddar.
- 7. Bake 20–25 minutes until bubbling; broil 2–3 minutes to brown. Rest 10 minutes before serving.
Why You’ll Love This Recipe
- Deep, pub-style flavor from a silky stout gravy with browned mushrooms.
- Creamy, sharp cheddar mash bakes into a golden, craggy crust.
- A complete, comforting meal in one pan—feeds a crowd with ease.
- Make-ahead friendly and freezer-ready for busy nights.
Grocery List
- Produce: Russet potatoes, onion, carrots, celery, cremini mushrooms, garlic, fresh thyme (or dried), chives (optional garnish)
- Dairy: Unsalted butter, sharp cheddar cheese, sour cream, milk, 1 egg
- Pantry: Olive oil, tomato paste, all-purpose flour, stout beer, beef broth, Worcestershire sauce, bay leaves, frozen peas, kosher salt, black pepper
Full Ingredients
Cheddar Mashed Potato Topping
- 2.5 lb (1.1 kg) russet potatoes, peeled and cut into 1.5-inch chunks
- 4 tbsp (56 g) unsalted butter
- 1.5 cups (about 6 oz / 170 g) sharp cheddar cheese, freshly grated
- 1/2 cup (120 ml) sour cream
- 1/2 cup (120 ml) whole milk, warmed
- 1 large egg yolk
- 1.25 tsp kosher salt (or to taste)
- 1/2 tsp freshly ground black pepper
Beef, Mushroom & Stout Filling
- 2 tbsp olive oil
- 1 tbsp unsalted butter
- 12 oz (340 g) cremini or baby bella mushrooms, sliced
- 1 large yellow onion, finely diced
- 2 medium carrots, finely diced
- 2 celery ribs, finely diced
- 4 garlic cloves, minced
- 1.5 lb (680 g) 85% lean ground beef
- 2 tbsp tomato paste
- 2 tbsp all-purpose flour
- 1 cup (240 ml) stout beer
- 1 cup (240 ml) beef broth (low sodium preferred)
- 2 tbsp Worcestershire sauce
- 1 tbsp fresh thyme leaves (or 1 tsp dried)
- 2 bay leaves
- 1 cup (140 g) frozen peas
- 1.5 tsp kosher salt (divided, adjust to taste)
- 3/4 tsp freshly ground black pepper (divided, adjust to taste)
- Optional: 1 tsp balsamic vinegar or malt vinegar (rounds out bitterness)
To Finish
- 1/2 cup (about 2 oz / 57 g) sharp cheddar, grated (for topping)
- Chopped chives or thyme leaves, for garnish (optional)

Step-by-Step Instructions
Step 1: Heat the oven and start the potatoes
Preheat the oven to 400°F (200°C). Place the peeled, cubed potatoes in a large pot, cover with cold water by 1 inch, and add 1 tablespoon kosher salt. Bring to a boil, then reduce to a lively simmer and cook until a knife slips in easily, 12–15 minutes.
Step 2: Brown the mushrooms
While the potatoes cook, heat 2 tbsp olive oil and 1 tbsp butter in a large skillet over medium-high heat. Add the sliced mushrooms in an even layer with a pinch of salt and cook undisturbed for 3–4 minutes to sear. Stir and continue cooking until well browned and their moisture evaporates, about 6–8 minutes total. Transfer to a bowl.
Step 3: Build the aromatic base and brown the beef
In the same skillet, reduce heat to medium. Add the onion, carrot, and celery with 1/2 tsp salt and cook, stirring, until softened and lightly golden, 6–8 minutes. Add the garlic and cook 30 seconds. Crumble in the ground beef, season with 1/2 tsp salt and 1/4 tsp pepper, and cook, breaking it up, until browned and no longer pink, 5–7 minutes. Stir in the tomato paste; cook 1 minute to caramelize slightly.
Step 4: Make the stout gravy
Sprinkle the flour over the meat and vegetables and cook, stirring, for 1 minute. Pour in the stout, scraping up browned bits. Add the beef broth, Worcestershire, thyme, bay leaves, and the browned mushrooms. Bring to a simmer and cook until glossy and thick enough to coat a spoon, 15–20 minutes, stirring occasionally. If desired, stir in 1 tsp vinegar to balance. Remove bay leaves. Stir in the frozen peas. Taste and season with additional salt and pepper as needed.
Step 5: Mash the potatoes with cheddar
Drain the potatoes well and return them to the hot pot. Let steam-dry 1–2 minutes. Add 4 tbsp butter, sour cream, warm milk, 1.25 tsp salt, 1/2 tsp pepper, and the egg yolk. Mash until smooth and fluffy. Fold in 1.5 cups grated cheddar.
Step 6: Assemble the pie
Spread the beef and mushroom filling evenly in a 9×13-inch (or similar 3-quart) baking dish. Dollop the cheddar mash over the top and gently spread to the edges to seal. Use a fork to create ridges (they brown beautifully). Sprinkle the remaining 1/2 cup cheddar over the surface.
Step 7: Bake until bubbling and golden
Place the dish on a rimmed sheet pan to catch any drips. Bake at 400°F (200°C) for 20–25 minutes, until the edges bubble. For extra color, broil 2–3 minutes, watching closely to avoid burning.
Step 8: Rest and serve
Let the cottage pie rest 10 minutes to set for cleaner slices. Garnish with chopped chives or thyme if you like. Serve hot.
Pro Tips
- For deeper mushroom flavor, cook them in batches and don’t overcrowd the pan.
- Reduce the stout briefly after deglazing to mellow bitterness and concentrate flavor.
- Steam-dry potatoes before mashing to keep the topping fluffy, not watery.
- A forked pattern on the mash increases crispy, golden surface area.
- Set the baking dish on a sheet pan—any bubbling stays in the pan, not your oven.
Variations
- Gluten-Free: Substitute 1.5 tbsp cornstarch for the flour (slurry with cold broth); use gluten-free stout or beef broth.
- No Alcohol: Replace stout with beef broth and add 1 tsp malt or apple cider vinegar for depth.
- Meat Blend: Use half ground beef and half ground pork for a richer filling.
Storage & Make-Ahead
Refrigerate leftovers in an airtight container for up to 3 days. Reheat covered at 350°F (175°C) for 20–25 minutes, then uncover 5 minutes to re-crisp. Freeze tightly wrapped (unbaked or baked) for up to 3 months; thaw overnight in the refrigerator and bake at 375°F (190°C) until heated through, adding 10–15 minutes if starting from chilled. Make-ahead: Assemble up to 24 hours in advance; cover and refrigerate. Bake directly from cold at 400°F (200°C), adding 5–10 minutes to the bake time.
Nutrition (per serving)
Approx. 710 calories; 42 g fat; 44 g carbohydrates; 33 g protein; 4 g fiber; 980 mg sodium. Nutrition will vary based on brands and exact measurements.

