Creamy, fluffy, and full of flavor, this Mashed Potato Casserole is the perfect way to prepare mashed potatoes for a gathering. Everyone will be wowed by the flavor and this casserole can be made in advance, making it the perfect dish to entertain with!

Everyone loves mashed potatoes, but they are best served immediately after preparing. This casserole is the perfect compromise! It can be prepared several days in advance yet is rich, decadent, buttery, tangy, and delivers the classic comfort you crave in mashed potatoes.

The Perfect Holiday Potatoes

This recipe for mashed potato casserole is from my husband's family and is a must-make holiday side dish.

My mother-in-law graciously shared her recipe for what she refers to as, Holiday Potatoes, and the name fits for many reasons!

This casserole is rich, creamy, decadent, and yet it is EASY to make. Which when it comes to entertaining, especially during the holidays, easy is a must!
This is the perfect way to prepare mashed potatoes for a crowd. It can be prepared up to 2 days in advanced and then baked right before serving, instead of having to be prepare potatoes right before entertaining.
This casserole travels well, making it a great dish to bring to a pot-luck. You can opt to bake upon arrival or bake at home before leaving for your gathering and keep warm by placing it in a casserole carrier or covered with foil and warm with a warm towel. It should hold warm for up to 1 hour.
This recipe truly is perfect to pair with Baked Ham, Roasted Turkey, or New York Strip Roast, or any holiday main course.

Ingredients Needed

Potatoes: I prefer using peeled, russet potatoes for this casserole. But peeled Yukon gold potatoes are delicious as well in this recipe.
Cream Cheese: Cream cheese gives the potato casserole a tangy, creamy, almost cheesy consistency. It is what makes this casserole so delicious! Use full fat or ⅓ less fat cream cheese, but do not use fat-free cream cheese for best results. And be sure your cream cheese is at room temperature to easily incorporate into the potato mixture.
Sour Cream: Sour cream is a must when making mashed potatoes in my book. The sour cream keeps the potatoes light, gives them a bit of tang, and makes them so much more luscious! Use full fat or reduced fat. Do not use fat-free sour cream--it can separate when baked.
Onion: I love the flavor of freshly minced onion in these potatoes. Feel free to omit or use 1 tablespoon dried onion flakes in place of the raw onion.
Butter: Potatoes and butter go hand and hand! I recommend using traditional unsalted butter. That way you can control the salt. Traditional butter is best --do not use margarine or a tub of refrigerated butter. The taste of real butter can not be replaced.
Eggs: The eggs will help the potatoes puff up a bit and give this casserole a bit of body. If you have an egg allergy, you can omit the eggs without sacrificing much.

Step-by-Step Directions

Step One: Cook Potatoes

Place cubed potatoes in a large stock pan. Cover with cold water and salt well.
Bring the mixture to a rapid boil, then reduce the heat to medium. Simmer until the potatoes are fork-tender.
Drain the potatoes and return to the hot pan.
Place over low heat and simmer until all the moisture has evaporated–about 1-2 minutes. This trick really helps keep the casserole from being watered down and helps to intensify the flavor of the potatoes.

Step Two: Mash Potatoes

In a large bowl, mash hot potatoes with a potato masher until nearly completely broken down.
Mix in cream cheese, butter, sour cream, milk, eggs, onion, salt, and pepper.
Beat the potato mixture with a handheld mixer until light and fluffy.

Normally, I do not recommend using a handheld mixture to mash potatoes as the potatoes can get gummy. But by using a potato masher to mash the cooked potatoes in advance, this will ensure that it will not take long to beat the remaining ingredients into the potatoes, so they will remain light and fluffy instead of gummy and tough.

Step Three: Refrigerate or BAKE

Place the whipped potato mixture into a buttered casserole dish.

At this point, you can cover the casserole dish and refrigerate for up to 48 hours OR you can bake until the casserole is warmed through and the potatoes are browned slightly on the top.
Once baked, dish out and serve.

Make-Ahead Directions

This mashed potato casserole is delicious and a perfect holiday side dish because it is the BEST way to prepare mashed potatoes in advance.

Simply prepare as directed up to baking. Then cover the casserole dish with plastic wrap and refrigerate for up to 48 hours. When ready to serve, remove from refrigerate and preheat the oven to 350 degrees. Remove the plastic wrap and bake for 45-50 minutes, or until slightly browned and warmed through.

Optional Flavor Additions

Cheesy Mashed Potato Casserole: Mix in 1 cup of shredded or cubed cheddar cheese into the potato mixture before spreading in the casserole dish and then top with 1 to 2 cups of additional shredded cheddar cheese and then bake as directed.
Loaded Mashed Potato Casserole: Before baking, top the potatoes with 2 cups shredded cheese and ½ cup crumbled cooked bacon. Bake as directed and then top with minced chives or green onions if desired.
Onion Mashed Potato Casserole: Add in ¼ cup finely minced onions and 1 teaspoon onion powder into the mashed potato mixture before beating. Bake as directed.

Recipe Notes

Store leftover baked mashed potato casserole in the refrigerator for up to 4 days and reheat individual servings in the microwave, covered with a damp paper towel so the casserole does not dry out.
You can opt to freeze the leftover casserole in an air-tight storage container or freezer bag for up to 1 month. Defrost in the refrigerator. Mix gently to incorporate and then reheat before serving.
The leftover casserole is delicious as the filling for Pierogi Lasagna--out of this world good!

More Delicious Holiday Side Dishes

Sweet Potato Casserole--This sweet potato casserole is also a great make-ahead holiday side dish and is made with maple syrup and perfectly spiced.
Classic Stuffing--This bread stuffing is not complicated, but the classic flavors are just what you crave on the holidays.
Roasted Butternut Squash Salad--The ingredients for this salad can be prepped in advance and then tossed before serving for a sweet, savory salad that delivers on flavor.
Green Beans Almondine--This is a simple way to dress up green beans that everyone loves!
Green Bean Casserole--All the classic flavors of the classic green bean casserole, made from scratch!
Holiday Salad--Made with tender greens, fresh oranges, and a champagne vinaigrette, this holiday salad is light, refreshing, and full of flavor.

I hope you love this mashed potato casserole as much as my family does and be sure to leave a comment and review below! I love hearing from you!

Mashed Potato Casserole

The Perfect Holiday Potatoes

Ingredients Needed