Loaded Mashed Potato Casserole

When it comes to comfort food, it’s hard to beat a bubbling mashed potato casserole straight out of the oven. This version takes your classic mashed potatoes and turns them into something spectacular — creamy, buttery potatoes blended with sour cream, cream cheese, and cheddar, then baked until golden and topped with crispy bacon and green onions. It’s cozy, crowd-pleasing, and make-ahead friendly — perfect for holidays, Sunday dinners, or any time you need a side dish that steals the show.

Serve it with my Crispy Chicken Bites with Honey Mustard Dip for a comforting, kid-approved dinner.

Yield
6-8 servings

Prep Time
25 mins

Cook Time
20 mins

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Ingredients

2 lbs (900g) russet potatoes, peeled and chopped
6 slices (about 60g total) cooked bacon, crumbled
⅓ cup (80g) sour cream, at room temperature
3oz (85g) cream cheese, softened
3 tbsp (42g) unsalted butter
3 tbsp (45ml) milk
1⅓ cup (140g) shredded cheddar cheese, divided
½ tsp garlic powder
salt and black pepper to taste (I would start with ½ tsp each)
2 green onions, sliced (for garnish or mixed in)

Instructions

Step 1.

Cook the potatoes. Place 2 lbs (900g) russet potatoes, peeled and chopped in a large pot of salted water. Bring to a boil and cook until fork-tender, about 15–20 minutes. While the potatoes are cooking, preheat your oven to 375°F (190°C).

A fork testing a boiled potato cube for doneness over a pot of simmering potatoes on the stove.

Step 2.

Mash it all up. Drain the cooked potatoes well and return them to the warm pot or a large mixing bowl. Add ⅓ cup (80g) sour cream, 3oz (85g) cream cheese, softened, 3 tbsp (42g) unsalted butter, and 3 tbsp (45ml) milk. Mash until smooth and creamy — you can leave a few small lumps if you like a rustic texture.

A pot filled with boiled potatoes, sour cream, butter, and cream cheese, ready to be mashed together.

Step 3.

Mix in the good stuff. Stir in half of the shredded cheddar cheese (about 2/3 cup or 70g) and most of the crumbled bacon, reserving some for topping. Season with ½ tsp garlic powder, salt and black pepper. At this stage, it’s best to taste the mashed potato and add salt and pepper to your liking.

Mashed potato mixture with cheese and bacon spread evenly in a beige Staub baking dish before baking.

Step 4.

Assemble the casserole. Lightly grease your 10.5×7.5-inch (2.7-quart) baking dish, then spread the mashed potato mixture evenly inside. Smooth the top with a spatula. Sprinkle with the remaining 2/3 cup (70g) cheddar cheese. Bake for 20 minutes, or until hot, bubbly, and lightly golden on top.

The mashed potato casserole topped generously with shredded cheddar and mozzarella cheese before baking.

Step 5.

Garnish with 2 green onions, sliced and reserved bacon before serving warm. Creamy, cheesy, and bacon-loaded — the ultimate cozy side dish!

Freshly baked mashed potato casserole in a beige Staub dish, topped with melted cheese, crispy bacon, and green onions.

Cook’s Notes

This recipe fits perfectly in a 10.5×7.5-inch (2.7-quart) baking dish, but you’ve got plenty of flexibility. An 8×8-inch square pan (2-quart) works too — just expect a slightly thicker layer and reduce the bake time by about five minutes. An 11×7-inch rectangular pan (2.5–3 quart) is almost identical in volume, so you can bake it as written. A 9×9-inch square pan (2.8-quart) will yield a shallower casserole, so start checking a few minutes early. If you’re feeding a crowd, go for a 9×13-inch pan (3.9-quart) and multiply the recipe by 1.5× to fill it nicely. You can even use individual 6–8 oz ramekins for mini servings — bake those for about 15–18 minutes, or until bubbly and golden.

Bake until the top is beautifully golden and the edges are gently bubbling — that’s your cue it’s ready to serve. For an extra toasty finish, switch the oven to broil for about 2 minutes to lightly brown the cheese (watch closely so it doesn’t burn!).

You can also make this mashed potato casserole up to two days ahead. Assemble it completely (without baking), cover tightly with plastic wrap or foil, and refrigerate. When ready to serve, let it sit at room temperature for about 30 minutes, then bake at 350°F (175°C) for 25–30 minutes or until heated through and the cheese is melted.

Leftovers keep well in the fridge for up to three days — just reheat in the oven or microwave until warm and creamy again (and maybe add a little extra cheese on top for good measure).

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