Mashed Potato Casserole

Try this mashed potato casserole for when you are looking for a way to make instant mashed potatoes into something tastier. This recipe for Cheesy Mashed Potato Casserole combines mashed potatoes, sour cream, herbs, cheese, and more!

mashed potato casserole with cheese and crispy fried onions on top.

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Cheesy Mashed Potato Casserole

This recipe for cheesy mashed potato casserole is a unique potato side dish. It’s a casserole that combines mashed potatoes, sour cream, herbs, cheese, and crispy fried onions.

Try this mashed potato casserole with sour cream when you are looking for a way to make instant mashed potatoes into something tastier. This comfort food potato dish will be the star of your next meal.

This potato casserole recipe is comfort food in a big ole’ casserole dish: These creamy, cheesy mashed potatoes are exactly the most satisfying food to scoop up when it’s bleak and chilly outside. They’re a must-have for your winter table.

Why This is the Best Mashed Potato Casserole Recipe

This recipe is the best way to dress up mashed potatoes! This easy cheesy mashed potato casserole is so delicious that your family will ask for more every time.

It takes just a few simple ingredients and can be made in under 30 minutes.

This tasty side dish takes simple mashed potatoes up to a whole new level. The sour cream lends its signature tang to the potatoes, and then there’s the cheese….

This cheesy mashed potato casserole will make every other potato casserole look a bit boring by comparison. Stuffed full of delicious mashed potatoes, sour cream, and herbs and topped with shredded cheese and crispy fried onions, this casserole is even in-law approved!

Since this comfort food casserole bakes at the same temperature as many other dishes, you can be baking your entrée in the oven at the same time.

Recipe Ingredients

This recipe is a necessity when you have no time to shop for a long list of ingredients. All you need are the following:

  • Instant mashed potatoes
  • Sour cream
  • Dried chives
  • Dried parsley
  • Black pepper
  • Shredded cheddar cheese
  • French’s Fried Onions
mashed potato casserole ingredients.

Cheesy Mashed Potato Casserole Recipe – Ingredient Substitutions

  • Swap the sour cream for heavy cream or even cream cheese. If you want to reduce the fat content, use reduced-fat sour cream.
  • This recipe uses Cheddar cheese, which melts wonderfully. You could combine it with parmesan, which adds its own signature salty, nutty flavor.
  • Swap the Cheddar for fontina or gruyère, while pecorino is a great substitute for parmesan.
  • For a vegetarian version, substitute a vegan version of sour cream and use a vegetarian-type cheese.

What About Using Fresh Potatoes?

I must confess that I have often fed instant mashed potatoes to my guests. If you add a few extra ingredients, most people won’t even know the difference.

Let me just say that you can, of course, make this cheesy mashed potato casserole recipe with fresh potatoes. I would use about two pounds of potatoes when making this dish from scratch.

How to Make Mashed Potato Casserole

  1. Prepare 4 cups of instant mashed potatoes according to the package directions.
  2. Add sour cream, chives, parsley, and pepper to the potatoes.
  3. Place the mashed potato mixture in a 1 1/2-quart casserole dish.
mashed potato casserole mixture in a baking dish.
  1. Sprinkle cheddar cheese evenly on top.
  2. Place the crispy fried onions around the edge of the casserole.
  3. Bake at 350°F for about 20 minutes or until the cheese melts.

If you are making this dish ahead to reheat later, add the shredded cheese, but wait to top it with the fried onions until you are ready to reheat.

CopyKat Tip: Shred your own cheese. Cheese always melts better when shredded off the block. Pre-shredded bagged cheese contains anti-caking agents and preservatives that can hinder melting. 

mashed potato casserole with a scoop of it on a serving spoon.

Recipe Variations

  • Add some veggies – corn, peas, broccoli florets, diced bell peppers.
  • Sprinkle on some fresh chives or thin slices of green onions when you take it out of the oven.
  • Add more cheese and bacon crumbles to the topping. If you are not a fan of bacon, use cubed ham or sausage.
  • Crisp things up by adding some crispy, toasty panko to your topping. 
  • Add a little sweetness to every bite with some cooked, cubed sweet potatoes. 
  • French onion soup your casserole! Add in one or two sliced, caramelized onions and a half cup of beef broth. Top with thin slices of Swiss or Gruyere.

A Brief History of the Potato

The Incas in Peru were the first civilization to cultivate potatoes around 8,000 to 5,000 B.C. After the Spanish Conquistadors conquered Peru in 1536, they discovered potatoes and brought them to Europe.

Potatoes landed in the US in 1621 when Nathaniel Butler, the Governor of Bermuda, sent vegetables, including potatoes, to the Jamestown colony in Virginia. Farmers everywhere eventually discovered that potatoes were easy to grow.

In time, it became known that potatoes contained nearly all of the vitamins necessary for human sustenance. You can read much more about the long history of the potato.

Some Interesting Facts About Potatoes

In the 18th Century Antoine-Augustin Parmentier, a French pharmacist convinced the French to eat potatoes and saved thousands from starvation during the European famines in the 1700s.

In 1767, Parmentier created a feast for King Louis XIV that consisted solely of potato dishes, a concept he realized was possible after being imprisoned in Germany and fed only on a diet of potatoes. Benjamin Franklin, the American Ambassador to France, attended Parmentier’s feast.

  • During the Klondike gold rush in Alaska, (1897-1898), gold miners paid for potatoes in gold. Gold was plentiful but nutritious vegetables weren’t.
  • In 1995, the potato starred as the first vegetable to be grown in space. NASA and the University of Wisconsin created a technology that would enable astronauts to be fed on long space voyages. It is hoped that in future potatoes will help feed human colonies on distant planets.
overhead view of mashed potato casserole.

How to Serve Baked Mashed Potato Casserole

Many things go well with this potato side dish. This casserole is potato comfort food so deserves a robust entrée such as:

What Other Vegetables Go Well With Mashed Potatoes?

Add more color and nutrition to your table by pairing mashed potatoes with colorful vegetables, such as steamed green beans, honey roasted carrots, or peas and carrots

How to Store Leftover Mashed Potato Casserole

Store leftovers in an airtight container in the fridge for 3 to 5 days. One awesome thing about this potato casserole is that you can make it ahead and refrigerate it.

This is super helpful if you’re making several dishes for a holiday meal or a large family dinner.

Note: Leftover mashed potatoes make great potato pancakes for breakfast. You might also check out bubble and squeak, a way in which the Brits love to use up mashed potatoes and anything else just taking up space in their kitchens.

Can You Freeze Mashed Potato Casserole?

Yes, you can freeze mashed potatoes. Simply scoop the potatoes into a freezer-safe bag and squeeze out as much air as you can. The potatoes will last in your freezer for 4 to 6 months.

If you are making this potato casserole ahead to reheat later or freeze, add the cheese topping, but hold off on the fried onions until you reheat.

To reheat, let the potatoes thaw in the fridge overnight. Then place them in a casserole dish and bake at 350°F for about 25 minutes. Add more cheese on top and bake for an additional 5 minutes.

mashed potato casserole topped with cheese and fried onions.

Love Mashed Potatoes? Try these recipes!

Favorite Casserole Side Dish Recipes

Check out more of my easy side dish recipes and the best casserole recipes here on CopyKat!

mashed potato casserole with cheese and crispy fried onions on top.

Mashed Potato Casserole

This cheesy mashed potato casserole is so hard to resist. Break out those French fried onions and upgrade your mashed potatoes.
5 from 7 votes
Print Pin Rate Add to Collection
Course: Side Dish
Cuisine: American
Keyword: mashed potato casserole, Potato Recipes
Prep Time: 10 minutes
Cook Time: 20 minutes
Total Time: 30 minutes
Servings: 8
Calories: 236kcal


  • 4 cups instant mashed potatoes
  • 3/4 cup sour cream
  • 1 teaspoon dried chives
  • 1 teaspoon dried parsley
  • 1/2 teaspoon black pepper
  • 3/4 cup shredded cheddar cheese
  • 1 cup French's Crispy Fried Onions


  • Preheat the oven to 350°F.
  • Prepare the instant mashed potatoes according to the package directions.
  • Add sour cream, chives, parsley, and pepper.
  • Place the mashed potatoes in a 1 1/2-quart casserole dish.
  • Top with cheddar cheese.
  • Sprinkle French's Fried Onions around the edge of the casserole.
    If you are making this dish ahead to reheat later, add the shredded cheese, but wait to top with French’s Fried Onions until you are ready to reheat.
  • Bake for about 20 minutes or until the cheese melts.


Calories: 236kcal | Carbohydrates: 28g | Protein: 5g | Fat: 11g | Saturated Fat: 6g | Cholesterol: 22mg | Sodium: 173mg | Potassium: 388mg | Fiber: 2g | Sugar: 1g | Vitamin A: 660IU | Vitamin C: 28.5mg | Calcium: 113mg | Iron: 0.6mg

About Stephanie Manley

I recreate your favorite restaurant recipes, so you can prepare these dishes at home. I help you cook dinner, and serve up dishes you know your family will love. You can find most of the ingredients for all of the recipes in your local grocery store.

Stephanie is the author of's Dining Out in the Home, and's Dining Out in the Home 2.

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Reader Interactions


  1. Winniebear

    5 stars
    Before I go shopping for the week I always check the fridge to see what needs to be used up and plan my meals/groceries accordingly. This seems like the absolute perfect medium to do that since potatoes are a great blank palette. Thank you Stephanie for sharing!!

  2. Laurie

    I would like to make the Cheesy Mashed Potato Casserole but what do you mean by 4 cups instant mashed potatoes? Does that mean 4 cups of the potato flakes and then follow package directions or 4 cups of prepared instant mashed potatoes? Sorry if question is dumb but I am still in training when it comes to kitchen duty. Thank you.

  3. Tomtom

    5 stars
    This was a potato casserole my mother-in-law enjoyed, which was surprising. She is very picky, and has told me that plain baked potatoes with nothing on them are “too salty”. Sometimes I stare at her and think my husband must have been adopted.

5 from 7 votes (2 ratings without comment)

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