Cheesy Loaded Mashed Potato Casserole with Bacon

When it comes to comfort food side dishes, nothing beats a rich and cheesy loaded mashed potato casserole. This recipe takes tender russet potatoes, crispy bacon, melty cheddar, cream cheese, and Boursin garlic & herb cheese to create the ultimate holiday or weeknight side. Perfect for Easter, Thanksgiving, or anytime you’re craving something indulgent, this casserole is easy to prepare, irresistibly cheesy, and guaranteed to impress a crowd.

Why You’ll Love This Loaded Mashed Potato Casserole Recipe

If you’ve ever wanted mashed potatoes to be the star of the table, this dish is it. By combining fluffy potatoes with butter, cream cheese, bacon, and two types of cheddar, this casserole delivers everything you love about loaded baked potatoes—just in a creamy, scoopable form. The addition of Boursin cheese takes the flavor over the top, making every bite bold and satisfying.

This is a go-to recipe when I’m hosting because it’s:

• Perfect for holidays and dinner parties
• Easy to make ahead and reheat
• Ready in under 45 minutes
• Loved by both kids and adults

Ingredients for Loaded Mashed Potato Casserole Recipe

• 4 medium russet potatoes
• 6–7 strips thick-cut bacon
• 1 cup yellow cheddar, shredded
• 1 cup white cheddar, shredded
• ½ package Boursin garlic & herb cheese
• 3 green onions (whites for cooking, greens for garnish)
• ½ yellow onion, diced
• 4 oz cream cheese, room temperature
• 1 tbsp garlic (fresh or paste)
• 3 tbsp butter
• 1 cup whole milk (or half & half/heavy cream)
• Salt, pepper, garlic powder, onion powder (to taste)

Step-by-Step Instructions for Loaded Mashed Potato Casserole Recipe

Step 1: Prep the Potatoes

Wash and peel 4 medium russet potatoes, then cut them into even bite-sized chunks so they cook evenly.

Rinse the pieces several times in cold water until it runs clear—this removes excess starch for fluffier mashed potatoes.

Add potatoes to a large pot, cover with water, season with 1 tbsp kosher salt, and bring to a boil. Cook until fork-tender, about 12–15 minutes. Drain well.

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Step 2: Crisp the Bacon

While the potatoes are boiling, arrange 6–7 strips of thick-cut bacon on a foil-lined baking sheet.

Bake at 425°F until crispy (about 12–15 minutes). Once done, transfer to a paper towel–lined plate and chop into bite-sized pieces. Reserve some for topping.

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Step 3: Grate the Cheese

While the bacon cooks, shred 1 cup of yellow cheddar and 1 cup of white cheddar using a box grater. Freshly grated cheese melts more smoothly and gives the casserole a creamier texture than pre-shredded cheese.

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Step 4: Sauté the Onions & Garlic

In a skillet, heat 1–2 tbsp bacon fat (or butter if preferred) over medium heat.

Add ½ diced yellow onion and the whites of 3 green onions, sautéing until soft and fragrant (about 3 minutes).

Stir in 1 tbsp garlic and cook for 1 more minute. Set aside.

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Step 5: Mash the Potatoes

In the same pot you boiled them in, mash the hot potatoes with a handheld masher.

Mix in:

• 4 oz cream cheese (softened)
• ½ package Boursin garlic & herb cheese
• 3 tbsp butter
• 1 cup whole milk (add gradually until creamy)

Stir until smooth and fluffy.

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Step 6: Load It Up

Fold in the sautéed onions, half the bacon, and half the shredded cheese. Taste and season with salt, pepper, garlic powder, and onion powder as needed.

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Step 7: Bake the Casserole

Transfer mashed potato mixture into a 9×11 casserole dish.

Spread evenly, then top with the remaining cheddar cheese. Bake at 375°F for 20 minutes until the cheese is bubbly and golden.

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Step 8: Garnish & Serve

Once baked, let the casserole rest for 10 minutes.

Top with the remaining crispy bacon, chopped green onion tops, and an extra sprinkle of cheddar if you like things extra cheesy. Serve hot with your favorite main dish!

Pro Tips for the Best Loaded Mashed Potato Casserole

• Don’t skip salting the water – this seasons the potatoes from within.
• Room temp cream cheese mixes smoother than cold.
• Make ahead: Assemble the casserole up to the baking step, refrigerate, then bake when ready to serve.
• Mix up your cheese: Try pepper jack, gouda, or mozzarella for new flavor twists.

Serving Ideas

This cheesy potato casserole pairs perfectly with:

• Glazed ham, roasted turkey, or grilled steak
• Green beans, roasted broccoli, or Caesar salad
• A crisp Chardonnay or sparkling cider

Try These Potato Recipes by Mr. Make It Happen

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