Cheesy Mashed Potato Casserole. the perfect Thanksgiving side dish.

Why This Mashed Potato Casserole Belongs on Your Thanksgiving Table

This mashed potato casserole is everything you want in a holiday side: warm, cheesy, creamy, and finished with a golden, crispy breadcrumb topping. It’s a delicious twist on classic mashed potatoes and ideal for making ahead — a total game changer when you’re juggling multiple dishes on Thanksgiving.

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Plus, it’s a great way to use up leftover mashed potatoes. Whether you're prepping for the big day or just making a cozy weeknight dinner, this casserole always hits the spot.

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• Mashed Potato Casserole

What Makes This Dish So Good?

Easy to Make Ahead
You can prep the entire casserole the night before and pop it in the oven when you’re ready to serve.

Comfort Food Favorite
The combination of melty cheese, smooth mashed potatoes, and buttery breadcrumbs is pure comfort.

Family-Approved
This dish is a hit with both kids and adults. You’ll definitely see second helpings going around the table!

The Taste and Texture

This casserole is ultra-creamy with a light tang from the sour cream and cream cheese. Freshly grated cheddar adds richness, while the breadcrumb topping gives it the perfect crunch. It’s like your favorite mashed potatoes — but with a crispy crown and a cheesy surprise in every bite.

Ingredients You’ll Need

• 3 lbs Russet potatoes (peeled and chopped)
• 3 tablespoon salt (for boiling water)
• 2¼ cups whole milk
• 1 cup butter (¾ cup for the mash, ¼ cup for the topping)
• 1 cup sour cream (room temperature)
• 1⅔ cups shredded cheddar cheese (divided)
• 8 oz cream cheese (room temperature)
• 1 teaspoon salt and 1 teaspoon pepper (adjust to taste)
• ½ cup plain breadcrumbs
• ½ tablespoon garlic salt

Tip: Freshly shred your cheese for the best melt and flavor.

How to Make Mashed Potato Casserole

Step 1: Cook the Potatoes
Boil the peeled and chopped potatoes in salted water for about 20–25 minutes until fork tender. Drain well.

Step 2: Scald the Milk
While the potatoes are cooking, heat the milk in a small saucepan until it just starts to boil. This helps it blend better with the potatoes.

Step 3: Mash and Mix
Use a potato masher or ricer to mash the hot potatoes. Gradually stir in the hot milk and ¾ cup butter until smooth. Add in the sour cream, cream cheese, 1 cup cheddar, salt, and pepper. Mix until well combined.

Step 4: Assemble
Spread the mashed potato mixture into a greased 2-quart baking dish.

Step 5: Add the Topping
Mix the breadcrumbs with the remaining ¼ cup melted butter and garlic salt. Sprinkle evenly over the potatoes.

Step 6: Bake
Bake at 350°F (175°C) for 20–25 minutes, or until the topping is golden and the edges are bubbling.

Helpful Tips for Perfect Results

• Use starchy potatoes like Russet or Yukon Golds for the fluffiest mash.
• Avoid overmixing, which can make your potatoes gummy.
• Don’t skip scalding the milk — it helps create that creamy texture.
• Prep ahead by assembling the casserole and refrigerating it overnight.

How to Serve Mashed Potato Casserole for Thanksgiving

Pair this cheesy mashed potato casserole with other classic holiday sides like:

• Green Bean Casserole – another make-ahead hero dish.
• Fresh Cranberry Sauce – a sweet and tart companion.
• Parmesan Roasted Baby Potatoes – perfect if you want more than one type of potato on the table!

For a full Thanksgiving spread, serve alongside a juicy roast, warm dinner rolls, and a crisp salad.

Storage and Reheating Tips

Storing Leftovers
Let the casserole cool completely. Store in an airtight container in the fridge for up to 4 days.

Freezing
Portion leftovers into individual containers and freeze for up to 2 months.

Reheating
Reheat in a 325°F oven until warmed through, or microwave in short bursts.

FAQs About Mashed Potato Casserole

Try a Flavor Twist

Want to change it up?

• Add a pinch of smoked paprika or cayenne for a little heat.
• Mix in chopped green onions or roasted garlic for a flavor boost.
• Swap the cheddar for mozzarella or a dairy-free alternative.

A Must-Try for Thanksgiving

Whether you’re building your Thanksgiving menu or just craving something cheesy and cozy, this mashed potato casserole is a must. It’s simple to make, easy to customize, and always gets rave reviews.

Tag your creations on Pinterest — I’d love to see how you serve it! And don’t forget to explore more of my Thanksgiving recipes to round out your holiday table.

Happy cooking and happy Thanksgiving!

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