Make-Ahead Cheesy Mashed Potato Casserole

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Cheesy mashed potato casserole with a crispy panko topping in a white baking dish.

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Make-Ahead Cheesy Mashed Potato Casserole

This cheesy mashed potato casserole is rich, creamy, and loaded with crispy bacon, cheddar, mozzarella, and chives, then finished with a buttery panko topping. It’s an easy make-ahead side dish for holidays or family dinners.

Prep Time10

Cook Time45

Total Time55

Course: Side Dish

Cuisine: American

Keyword: cheesy mashed potato casserole, mashed potato casserole

Servings:

Calories: 381kcal

Author: Jordan Zelesnick

Equipment

8x11 Baking Dish

Ingredients

3 lbs Yukon Gold potatoes peeled and cut into 3 inch pieces
6 tbsp unsalted butter softened
1 cup sour cream
1/2-3/4 cup whole milk as needed for consistency
Kosher salt and black pepper
6 slices bacon cooked crisp and chopped
1 1/2 cups shredded cheddar divided
1 1/2 cups shredded mozzarella
3/4 cup chopped chives or green onion divided
1 3/4 cup panko breadcrumbs
3 tbsp butter melted (for the panko)

Instructions

Boil the potatoes in generously salted water until fork-tender, about 15–20 minutes. Drain well.
3 lbs Yukon Gold potatoes
Using a hand masher, mash the potatoes in a large mixing bowl with the butter, and sour cream. Slowly add the milk and continue mashing until smooth and creamy. Season with salt and pepper.
6 tbsp unsalted butter, 1 cup sour cream, 1/2-3/4 cup whole milk, Kosher salt and black pepper
Fold in the bacon, ¾ cup of the cheddar, 1 cup of mozzarella, and half the chives/green onion.
6 slices bacon, 1 1/2 cups shredded cheddar, 1 1/2 cups shredded mozzarella, 3/4 cup chopped chives or green onion
Spread the mixture into a buttered 2.5 quart baking dish. Top with the remaining ½ cup of cheddar and ½ cup of mozzarella.
Toss the panko with the melted butter and sprinkle evenly over the top.
1 3/4 cup panko breadcrumbs, 3 tbsp butter
Bake at 375°F for about 20-25 minutes, until golden on top and cheese is bubbling.
Sprinkle the mashed potato casserole with the remaining chives/green onion before serving.

Notes

Baking dish: An 8×11-inch or 2½-quart baking dish works well.
Salt the water: Add 2–3 generous pinches of kosher salt to the water before boiling the potatoes. This seasons them from the inside out.
Add the milk gradually: Start with ½ cup and add more as needed until the potatoes are smooth and creamy.
Don’t overmix: A hand masher gives you the most control. If using an electric mixer, mix just until smooth—overmixing can make the potatoes gummy.

Make ahead: Prepare the casserole up to 2 days in advance, adding an extra ¼ cup milk so the potatoes stay creamy as they chill. Cover and refrigerate without the panko topping. Before baking, let it sit at room temperature for about 45 minutes, then add the cheese and buttered panko. Bake as directed, adding 10–15 minutes as needed until hot and bubbly.

Nutrition