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4.86 from 7 votes

Make-Ahead Cheesy Horseradish Mashed Potato Casserole

Take some of the stress out of serving a big holiday meal to a large group of people (or any meal for that matter) by preparing this cheesy horseradish mashed potato casserole in advance. They're zippy, creamy, and always a favorite at the dinner table.
Prep Time15 mins
Cook Time30 mins
Total Time45 mins
Course: Side Dish
Cuisine: Potatoes
Servings: 16 cups


  • 5 pounds of russet potatoes peeled and cut into 1½" cubes
  • 2 tablespoons salt
  • 3 quarts water
  • 1 cup warm milk
  • 8 tablespoons butter at room temperature
  • ½ cup prepared horseradish or to taste
  • 4 ounces cream cheese softened
  • 8 ounces shredded sharp cheddar cheese at room temperature
  • 1 teaspoon coarse ground black pepper
  • ¼ teaspoon freshly grated nutmeg or to taste


  • Add the prepared potatoes to a large stockpot and cover with cold water.
  • Cover the pot with a lid.
  • Bring the water to a low-boil and add 2 tablespoons salt. *Note - keeping a wooden spoon in the pot will stop any boilovers.
  • Reduce the heat slightly and simmer the potatoes until fork-tender (approximately 30 minutes).
  • Drain the potatoes and add them back into the hot pot.
  • Add the warm milk, room-temperature butter, and cream cheese into the potatoes and mash.
  • *Note - if ricing the potatoes, after draining, rice them into the hot pot and then add the remaining ingredients to the riced potatoes and stir.
  • Add the horseradish, shredded cheese, black pepper, additional salt (if desired, to taste) and grated nutmeg.
  • Mash again until you reach your desired consistency.
  • Add the cheesy horseradish mashed potatoes into a 13x9 casserole dish which has been sprayed with baking spray.
  • To refrigerate: Cool Completely. Cover with foil or plastic wrap and refrigerate for up to 2 days.
  • To freeze: Cool Completely. Cover with foil or plastic wrap and freeze for up to 2 months.
  • If serving immediately, place in a preheated 350-degree oven for 20 minutes, uncovered.


To serve after freezing; thaw completely and allow to come to room temperature. Cover and bake in a preheated 350-degree oven for 50 minutes, covered, and 10 minutes, uncovered, or until hot. Stir well before serving.
To serve after refrigeration: allow to come to room temperature (approximately 60 minutes). Cover and bake in a preheated 350-degree oven for 50 minutes, covered, and 10 minutes uncovered.


Serving: 1cup