Easy Cheesy Mashed Potato Casserole with Instant Potatoes
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This Easy Cheesy Mashed Potato Casserole turns simple instant potatoes into a rich, cheesy, comfort-food favorite.
It’s ready in about 30 minutes with no peeling or boiling.
If you need a side dish that’s fast, creamy, and guaranteed to disappear, this is it.
If you’ve been around here for a while, you know I love easy, no-stress recipes. Favorites like Crockpot BBQ Chicken, Mexican Enchilada Casserole, and Rotisserie Chicken Ritz Cracker Casserole are popular because they just work.
This cheesy mashed potato casserole is the same kind of recipe.
When I make it, it’s because I need a side dish I know everyone will eat. It’s creamy, cheesy, and always a hit.
Table of contents
Why You’ll Love This Recipe
- Uses instant potatoes (huge time saver)
- Extra creamy from sour cream + cream cheese
- Loaded with melty cheddar cheese
- Bakes into a hot, bubbly casserole
- Easy to double for a crowd
Ingredients You’ll Need
You only need a few simple ingredients to make this delicious side dish.
- Instant mashed potato flakes
- Milk, water, butter
- Sour cream
- Cream cheese
- Cheddar cheese
- Garlic powder, salt, pepper
Optional:
- Bacon
- Green onions
How to Make Cheesy Mashed Potato Casserole
Tips for the Best Mashed Potato Casserole
- Don’t skip the cream cheese, it makes it extra smooth
- Add a splash of milk if it feels too thick
- Let it sit a few minutes after baking so it sets up
- Add extra cheese on top if you want it more golden and bubbly
What to Serve With Mashed Potato Casserole
This goes with just about anything:
- BBQ chicken
- Meatloaf
- Baked chicken
- Holiday ham or turkey
It’s one of those sides that works for both weeknights and holidays.
Easy Variations
Loaded: Add bacon + green onions
Ranch: Mix in ranch seasoning
Spicy: Add jalapeños or pepper jack
Lighter: Use plain Greek yogurt instead of sour cream
Frequently Asked Questions
Yes. Assemble the casserole, cover, and refrigerate. Bake when ready (you may need to add a few extra minutes).
Absolutely. Use a 9×13 dish and double everything.
You can, but the texture is best fresh or refrigerated and reheated.
Yes. Colby Jack, mozzarella, or a blend all work great.
If you try this cheesy mashed potato casserole, I’d love to hear what you think. It’s one of those easy recipes I come back to again and again, and I hope it becomes a favorite for you too.
Be sure to leave a comment and a 5-star rating below. It really helps others find this recipe and lets me know you enjoyed it.
Easy Cheesy Mashed Potato Casserole with Instant Potatoes
Ingredients
- 1 ⅓ cup instant mashed potato flakes
- 1 ½ cups water
- ¾ cup milk
- 2 Tbsp butter
- ½ tsp salt
- ½ cup sour cream
- 4 oz cream cheese, softened
- 1 ½ cups shredded cheddar cheese, divided
- ½ tsp garlic powder
- ¼ tsp black pepper
Optional toppings:
- 4 slices cooked bacon, crumbled
- 2 Tbsp chopped green onions
Directions
- Preheat oven to 375°F and grease a 9×9 or small casserole dish.
- In a medium bowl, heat the water, butter, and milk until hot and just starting to boil (you can do this on the stove or in the microwave). Stir in the instant mashed potato flakes and let sit for 1–2 minutes, then fluff with a fork.
- Add the sour cream, cream cheese, 1 cup of the shredded cheddar cheese, garlic powder, salt, and pepper. Stir until smooth and creamy.
- Spread the mashed potato mixture evenly into the prepared baking dish. Sprinkle the remaining ½ cup cheddar cheese over the top.
- Bake uncovered for 20–25 minutes, until hot and bubbly and the cheese is melted.
- Top with crumbled bacon and green onions if desired before serving.
Notes
- You can use plain Greek yogurt in place of sour cream.
- Add a little extra milk if the mixture feels too thick.
- This recipe doubles easily for a 9×13 dish.
Nutrition Facts
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