Grandma always made her food with love, and this Mashed Potato Casserole was no exception. She’d make this casserole whenever the family was together, and we would all look forward to this simple dish, which was pure comfort food. You’ll love it, too. It’s easy to make, and you can prep it ahead of time so it’s ready to bake. What’s better than that? Check out Grandma’s Mashed Potato Casserole today!

Grandma's Mashed Potato Casserole and spoon.

This is the perfect simple Mashed Potato Casserole. You can prep it ahead of time and then just pop it into the oven to bake before serving. This means you can visit with your company, instead of being stuck in the kitchen.

Grandma used boxed mashed potatoes in this recipe, and I do, too. The boxed mashed potatoes are pretty darn good, and you’re going to jazz them up so much that nobody will know you started with a box of instant mashed potatoes.

I use 2 pouches of butter & herb flavor mashed potatoes because I like the extra flavor from them, but you can use whatever you like. 

If you’re craving a creamy, easy, and totally addictive side dish that’ll pair with so many other dishes, Grandma’s Mashed Potato Casserole is the dish for you!

Grandma's Mashed Potato Casserole on a tray.

What You’ll Love About Grandma’s Mashed Potato Casserole:

  • Easy to prepare with simple ingredients, and you can prep it ahead of time and bake when ready.
  • It’s perfect for family gatherings and holiday meals and it pairs so nicely with so many dishes. See all my suggestions below.
  • It’s equally delicious leftover, so don’t be afraid to make extra!

Ingredients:

  • Box of instant mashed potatoes
  • Sour cream
  • Cottage cheese
  • Fresh chives
  • Onion powder
  • Garlic powder
  • Butter – Divided.
Ingredients for Grandma's Mashed Potato Casserole.

How To Make Grandma’s Mashed Potato Casserole:

  1. Preheat your oven to 375-F and spray an 8×8-inch baking dish with nonstick cooking spray. Set aside.
  2. Make the mashed potatoes according to the package directions but add 1 cup less liquid than what is called for. 
  3. Mix in the sour cream, cottage cheese, onion powder, garlic powder, chives and 2 tablespoons of butter until well combined.
  4. Transfer the mixture to the prepared baking dish and dot the top with the remaining 1 tablespoon of butter.
  5. Bake in a preheated 375°F oven for about 15-20 minutes. Then, switch the oven to the broiler setting and broil for 2-3 minutes to brown the top.
  6. Serve hot, and enjoy the creamy, savory goodness of this comforting casserole.

Step-By-Step Process

Heather’s Tried-And-True Tips:

  • Use full-fat sour cream and cottage cheese for the richest flavor
  • If you prefer a cheesier version, mix in 1 cup of shredded cheddar cheese before baking
  • Let the casserole sit for 5 minutes before serving to make it easier to cut and serve
  • For a crispy topping, sprinkle some breadcrumbs or crushed Ritz crackers mixed with melted butter over the casserole before baking

Recommended:

Make It A Meal:

Grandma’s Mashed Potato Casserole pairs wonderfully with a variety of main dishes. For a complete meal, serve it alongside roasted chicken, grilled steak, or baked salmon. For a comforting, hearty dinner, consider pairing it with meatloaf or braised short ribs. Add a side of steamed green beans or a fresh garden salad to balance out the richness of the casserole.

Grandma's Mashed Potato Casserole in a black baking dish.

Storage:

Leftovers can be stored in an airtight container in the refrigerator for up to 3 days. To reheat, place the casserole in a preheated 350°F oven for about 15 minutes, or until heated through. You can also microwave individual portions.

Grandma's Mashed Potato Casserole in a black baking dish.

Grandma’s Mashed Potato Casserole

Heather S.
A delightfully easy recipe that's so much more than just mashed potatoes in a baking dish. Loaded with flavor, Grandma's Mashed Potato Casserole is super creamy and oh-so good! Perfect with ham, roasts, grilled meats, and more.
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Prep Time 10 minutes
Cook Time 20 minutes
Total Time 30 minutes
Course Side Dish
Cuisine American
Servings 8 servings
Calories 195 kcal

Ingredients
  

  • 1 box instant mashed potatoes  6.6-ounce box with 2 pouches
  • ¾ cup sour cream
  • 1 cup cottage cheese
  • 2 tablespoons fresh chives chopped
  • ½ teaspoon onion powder
  • ½ teaspoon garlic powder
  • 3 tablespoons butter divided

Instructions
 

  • Preheat your oven to 375-F and spray an 8×8-inch baking dish with nonstick cooking spray. Set aside.
  • Make the mashed potatoes according to the package directions but add 1 cup less liquid than what is called for.
  • Mix in the sour cream, cottage cheese, onion powder, garlic powder, chives and 2 tablespoons of butter until well combined.
  • Transfer the mixture to the prepared baking dish and dot the top with the remaining 1 tablespoon of butter.
  • Bake in a preheated 375°F oven for about 15-20 minutes. Then, switch the oven to the broiler setting and broil for 2-3 minutes to brown the top.
  • Serve hot, and enjoy the creamy, savory goodness of this comforting casserole.

Notes

Heather’s Tried-And-True Tips:

  • Use full-fat sour cream and cottage cheese for the richest flavor
  • If you prefer a cheesier version, mix in 1 cup of shredded cheddar cheese before baking
  • Let the casserole sit for 5 minutes before serving to make it easier to cut and serve
  • For a crispy topping, sprinkle some breadcrumbs or crushed Ritz crackers mixed with melted butter over the casserole before baking

Nutrition

Serving: 0.5cupCalories: 195kcalCarbohydrates: 22gProtein: 6gFat: 10gSaturated Fat: 5gPolyunsaturated Fat: 0.4gMonounsaturated Fat: 2gTrans Fat: 0.2gCholesterol: 28mgSodium: 149mgPotassium: 334mgFiber: 2gSugar: 2gVitamin A: 338IUVitamin C: 21mgCalcium: 53mgIron: 0.4mg
Tried this recipe?Let us know how it was!

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