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Creamy mashed potato casserole in a white baking dish with a golden top.

Creamy Mashed Potato Casserole

Rebecca Blumer
A rich, creamy mashed potato casserole with garlic, herbs, and a buttery golden top that is perfect for make-ahead holiday meals or cozy family dinners.
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Prep Time 30 minutes
Cook Time 1 hour 20 minutes
Total Time 1 hour 50 minutes
Course Side Dish
Cuisine American
Servings 8 Servings
Calories 416 kcal

Equipment

  • Large Pot
  • Colander
  • Food mill or potato ricer
  • Potato masher
  • Large Mixing Bowl
  • 2 1/2 quart baking dish

Ingredients
 

Mashed Potato Casserole

  • 3 pounds small russet potatoes peeled and cut into 3 inch chunks
  • 1 tablespoon kosher salt
  • 6 whole garlic cloves peeled
  • 1 bay leaf whole
  • 4 thyme sprigs about 3 inches long each
  • 1 package cream cheese 8 ounces, at room temperature
  • 6 tablespoons unsalted butter at room temperature
  • 1 cup sour cream full fat
  • 3/4 to 1 cup whole milk warmed
  • kosher salt to taste
  • freshly ground black pepper to taste
  • 2 tablespoons unsalted butter cut into bits and chilled

Instructions
 

  • Generously butter a shallow 2 1/2 quart gratin or baking dish and set it aside so the mashed potato casserole releases easily and develops flavorful edges as it bakes.
  • Place the peeled and chopped russet potatoes in a large pot and cover with cold water by about 2 inches. Add the kosher salt, peeled garlic cloves, bay leaf, and thyme sprigs. Bring to a boil, then reduce the heat, partially cover, and simmer until the potatoes are just tender when pierced with a knife, about 20 minutes. Drain very well, then let the potatoes steam dry until the edges look slightly chalky, about 3 minutes. Discard the bay leaf and thyme stems.
  • While the potatoes are still hot, press them and the cooked garlic through a food mill or potato ricer into a large bowl. If you do not have one, mash the potatoes as smoothly as possible with a hand held potato masher, avoiding any electric tools that can overwork the starch.
  • Add the cream cheese, room temperature butter, sour cream, and 3/4 cup of the warmed whole milk to the hot potatoes. Stir gently until the mixture is smooth and fluffy, adding a little more warm milk if needed so the texture is slightly looser than you want at serving time. Season to taste with additional kosher salt and freshly ground black pepper.
  • Scrape the mashed potatoes into the prepared baking dish and smooth the top with a spatula. Dot the surface evenly with the chilled butter bits. Let the casserole cool completely at room temperature, then cover tightly with plastic wrap and refrigerate overnight or for up to 2 days.
  • When ready to bake, preheat the oven to 350°F. Remove the casserole from the refrigerator and let it stand at room temperature for about 30 minutes. Uncover and bake until the top is golden brown and the potatoes are heated through to the center, about 1 hour. Serve the mashed potato casserole warm.

Notes

This mashed potato casserole can be assembled up to 2 days ahead, chilled, then baked until hot and golden. Leftovers keep well in the fridge for up to 4 days and reheat nicely in the oven or microwave.

Nutrition

Calories: 416kcalCarbohydrates: 36.7gProtein: 7.4gFat: 27.9gSaturated Fat: 16.4gSodium: 634.2mgFiber: 2.7gSugar: 4.5g
Keyword holiday potato side dish, make ahead mashed potatoes, mashed potato casserole
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