Cheesy Mashed Potato Casserole

This cheesy mashed potato casserole is the kind of easy side dish that makes a weeknight dinner feel like a special occasion. It starts with instant mashed potatoes, which get a boost from tangy sour cream, dried chives and parsley, and a little black pepper. Then it's topped with cheddar cheese and crispy fried onions, so every scoop has creamy, cheesy, and crunchy bits all at once. It's comfort food that comes together in about 30 minutes, and it bakes right alongside your main dish at 350°F.

What Makes This Mashed Potato Casserole a Crowd Pleaser

• It's ready in under 30 minutes, thanks to instant mashed potatoes, so you can have a comforting side dish even on busy nights.
• The sour cream and herbs give the potatoes a bright, tangy flavor that pairs well with rich mains like roast chicken or meatloaf.
• The crispy fried onions add a crunchy topping that contrasts with the creamy potatoes, and they stay crisp if you add them right before serving.

Ingredient Notes for This Mashed Potato Casserole

• Instant mashed potatoes: Use a good brand like Idahoan or Betty Crocker. The flakes should be light and fluffy. You can also use leftover homemade mashed potatoes, but you'll need to adjust the seasoning and possibly add a little more sour cream to keep them creamy.
• Sour cream: Full-fat sour cream gives the best texture and tang. Low-fat can make the potatoes watery. If you're out, plain Greek yogurt works as a substitute.
• Cheddar cheese: Sharp cheddar adds more flavor than mild. Grate it yourself for better melting, since pre-shredded cheese often has anti-caking agents that can affect texture.

Kitchen Tools for Making This Mashed Potato Casserole

• 1 1/2-quart casserole dish for baking the casserole
• Mixing bowl for combining the potatoes with the sour cream and herbs
• Measuring cups and spoons for accurate ingredient amounts
• Rubber spatula or spoon for stirring and spreading the potatoes evenly

Tips for Making the Best Mashed Potato Casserole

• Stir the sour cream and herbs into the potatoes gently. Overmixing can make the potatoes gluey.
• Use a 1 1/2-quart casserole dish so the potatoes are about 2 inches deep. A larger dish will make them spread too thin and bake faster.
• Bake just until the cheese melts, about 20 minutes. If you leave it in longer, the potatoes can dry out.

Pro Tips for the Creamiest Mashed Potato Casserole

• Use full-fat sour cream for the creamiest texture. Low-fat or nonfat sour cream can make the potatoes watery.
• Let the casserole rest for 5 minutes after baking. This lets the cheese set and makes serving easier.
• If you want a golden, bubbly top, switch the oven to broil for the last 1 to 2 minutes, but watch it closely so the onions don't burn.

Variations for This Mashed Potato Casserole

• Add 1/2 cup of cooked, crumbled bacon to the potato mixture for a smoky flavor.
• Swap the cheddar for pepper jack cheese to add a little heat.
• Mix in 1/2 teaspoon of garlic powder or a minced garlic clove with the sour cream.
• Use Greek yogurt instead of sour cream for a tangier, lighter version.

What to Serve with This Mashed Potato Casserole

Toppings

• Extra shredded cheddar cheese for a cheesy finish
• Chopped fresh chives or parsley for a pop of color
• Crumbled cooked bacon for a smoky, salty crunch

Side Dishes

• Roast chicken or turkey for a classic comfort food pairing
• Grilled steak or pork chops for a hearty meal
• Meatloaf or meatballs for a family-friendly dinner

How to Store Leftover Mashed Potato Casserole

Store leftover casserole in an airtight container in the refrigerator for up to 4 days. The fried onions will soften, but the flavor will still be good. To keep the topping crisp, you can reheat in the oven and add a few fresh fried onions on top. If you're meal prepping, you can also assemble the casserole without the onions, cover, and refrigerate for up to 2 days before baking.

Can You Freeze This Mashed Potato Casserole?

Yes, you can freeze this casserole. Assemble the casserole without the fried onions, cover tightly with foil, and freeze for up to 2 months. When you're ready to bake, thaw it overnight in the refrigerator, then bake at 350°F for about 25 minutes, or until heated through. Add the fried onions during the last 5 minutes of baking so they stay crispy. If you freeze after baking, let it cool completely, then wrap and freeze. Reheat in the oven at 350°F until warmed through.

How to Reheat Leftover Mashed Potato Casserole

To reheat leftover mashed potato casserole, place it in a 350°F oven for about 15 minutes, or until warmed through. If you're reheating a single serving, the microwave works fine, but the fried onions will lose their crunch. For the best texture, reheat in the oven and add a fresh sprinkle of fried onions if you have them. If you made the casserole ahead and added the cheese but not the onions, add the onions when you reheat so they stay crispy.

Source recipe: Cheesy Mashed Potato Casserole (SnapChef ID 9029d812-1e25-4a62-b8b0-659d0d7c57ef). Nutrition is estimated per serving.

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Cheesy Mashed Potato Casserole

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Prep Time

10 min

Cook Time

20 min

Total Time

30 min

Servings

8 servings

Calories

236 kcal

Scale: 1x2x3x · − 8 servings +

US Metric

Cook Mode

Ingredients

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• 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

Directions

1. 1
   Preheat the oven to 350°F.
2. 2
   Prepare the instant mashed potatoes according to the package directions.
3. 3
   Add sour cream, chives, parsley, and pepper.
4. 4
   Place the mashed potatoes in a 1 1/2-quart casserole dish.
5. 5
   Top with cheddar cheese.
6. 6
   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.
7. 7
   Bake for about 20 minutes or until the cheese melts.

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Nutrition Facts per serving · estimated

Amount per serving

Calories 236 kcal 12% DV

Protein 5 g 10% DV

Total Fat 11 g 14% DV

Total Carb. 28 g 10% DV

Fiber 2 g 7% DV

Sugars 1 g

Sodium 173 mg 8% DV

% Daily Values are based on a 2,000-calorie diet (FDA).