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top view of holding mashed potato casserole recipe showing the panko topping, cheeses, bacon and, green onions
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Mashed Potato Casserole Recipe

This MAKE AHEAD FRIENDLY Mashed Potato Casserole is 10/10 creamy, cheesy, and flavor-packed! I’ve perfected the recipe with a buttery, crunchy panko topping, savory spices, and melty cheeses to make it irresistibly crowd-pleasing every time. See the post for expert tips, make-ahead instructions, step-by-step photos, and recipe variations!
Course Side Dish
Cuisine American
Prep Time 30 minutes
Cook Time 55 minutes
Total Time 1 hour 25 minutes
Servings 12 -14 servings
Author [email protected]

Ingredients

  • 4 lbs. Russet potatoes, peeled, cut into 1-inch chunks
  • 1 1/2 tablespoons kosher salt (for boiling potatoes)
  • 3/4 cup full fat sour cream
  • 4 oz. full fat, brick-style cream cheese, cubed, very soft
  • 8 tablespoons unsalted butter cubed, very soft
  • 1 tsp EACH onion powder, garlic powder, dried parsley, table salt
  • 1/2 tsp EACH smoked paprika, dried thyme, dried dill weed
  • 1/4 teaspoon pepper
  • 3/4 cup milk (2% or whole), warmed (See notes for Make Ahead)
  • 1/2 tightly packed cup (2 oz.) freshly shredded Gouda (smoked if you love it)
  • 1/2 tightly packed cup (2 oz.) freshly shredded Gruyere

Panko Topping

  • 2 tablespoons unsalted butter
  • 1 tablespoon olive oil
  • 2/3 cup panko breadcrumbs
  • 1/2 tightly packed cup (2 oz.) freshly shredded Gouda
  • 1/2 tightly packed cup (2 oz.) freshly shredded Gruyere
  • 5 slices thick cut bacon, cooked and crumbled
  • 1/3 cup chopped green onions

Instructions

  • Prep: Preheat the oven to 375°F. Lightly grease a 9x13 baking dish with butter or cooking spray.
  • Boil Potatoes: Place the cubed potatoes in a large Dutch oven and fill with water so it reaches about 2 inches above the potatoes. Cover and bring to a boil, then season with 1 1/2  tablespoons of kosher salt. Reduce to a simmer with the lid partially covering the pot until the potatoes are very soft, about 15 minutes (if you pierce them with a fork, they should fall apart).
  • Toast Panko: While the potatoes are boiling, melt 2 tablespoons of butter with one tablespoon of olive oil in a large skillet. Add the panko and toast over medium heat until golden. Transfer to a plate to stop cooking.
  • Drain: Drain the potatoes very well in a colander, then return them to the pot to steam-dry for 3 minutes.
  • Mash: Add the sour cream, cream cheese, butter, and spices, and mash using a potato masher (not a mixer) until smooth. Gradually stir in the warmed milk with a spatula until smooth. IF MAKING AHEAD, stir in an extra 1/4 cup of warmed milk.
  • Add Cheeses: Stir in the cheeses. Don’t overmix, or they can be gluey. The potatoes will be slightly softer/looser than desired because they will firm up when baked or chilled.
  • Assemble: Spread the potatoes into the prepared baking dish, then top with cheeses and panko.
  • Bake: Cover with foil and bake for 25 minutes. Uncover and bake an additional 10 minutes, until the cheese is completely melted.
  • Serve: Top with green onions and bacon. Dig in!

Notes

MAKE AHEAD
Keep the panko topping in an airtight container at room temperature until ready to bake. Add an additional 1/4 cup of warm milk when mashing, as the potatoes will dry out a little in the refrigerator. When ready to bake, let the casserole sit at room temperature for 1 hour to bake evenly. Add the panko, then bake, covered, for 35 minutes. Uncover and bake for an additional 10 minutes, or until the cheese is melted and the casserole is warmed through.