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Mashed Potato Casserole
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Creamy Mashed Potato Casserole with Beef and Cheese

Creamy, cheesy, and deeply comforting, this mashed potato casserole combines fluffy potatoes, savory beef, and melted cheese into a crowd-pleasing dish that’s perfect for family dinners or make-ahead gatherings.
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Prep Time 25 minutes
Cook Time 30 minutes
Total Time 55 minutes
Servings: 6 servings
Course: Dinner, Side Dish
Cuisine: American
Ingredients Method Notes

Ingredients
  

  • For the Mashed Potato Base
  • 1.75 kg / 3.5 lb potatoes Russet, Maris Piper, King Edwards, or similar starchy potatoes – peeled and cut into chunks
  • 1 tbsp cooking or kosher salt – for boiling the potatoes
  • ⅔ cup whole milk – warmed slightly for smoother mashing
  • ⅔ cup extra milk – only if making ahead to keep the potatoes creamy
  • 75 g 5 tbsp unsalted butter – cut into small cubes
  • ½ cup full-fat sour cream or yogurt – for richness and tang
  • 1 tsp cooking or kosher salt – or to taste
  • For the Topping
  • 1 ½ cups freshly shredded mozzarella – for stretch and melt
  • 1 cup shredded cheddar Red Leicester, or flavored cheese – for depth of flavor
  • 200 g / 6 oz streaky ground beef – chopped
  • ¼ cup green onions – finely sliced for garnish

Method
 

  1. Place ground beef in a cold non-stick skillet and cook over medium heat, breaking it up gently as the fat renders. Increase heat and cook until golden. Drain and set aside.
  2. Boil the peeled and chopped potatoes in salted water until very tender. Drain well and return to the hot pot to evaporate excess moisture.
  3. Add milk, butter, sour cream, and salt to the potatoes. Mash gently until smooth and fluffy.
  4. Preheat oven to 200°C / 400°F. Spread mashed potatoes into a greased baking dish.
  5. Top evenly with shredded cheeses and cooked beef. Cover loosely with foil.
  6. Bake for 20 minutes (or 35 minutes if made ahead). Remove foil and bake 10 more minutes until bubbly and lightly golden.
  7. Garnish with sliced green onions and serve hot.

Notes

Use starchy potatoes only for the best texture. Avoid overmixing to keep the potatoes light and fluffy. Ground turkey can be substituted for beef if preferred.