Make-Ahead Cheesy Mashed Potato Casserole

Name: Make-Ahead Cheesy Mashed Potato Casserole
Prep time: 10 min
Cook time: 45 min
Total time: 55 min
Ingredients: 3 lbs Yukon Gold potatoes (peeled and cut into 3 inch pieces); 6 tbsp unsalted butter (softened); 1 cup sour cream; 1/2-3/4 cup whole milk (as needed for consistency); Kosher salt and black pepper; 6 slices bacon (cooked crisp and chopped); 1 1/2 cups shredded cheddar (divided); 1 1/2 cups shredded mozzarella; 3/4 cup chopped chives or green onion (divided); 1 3/4 cup panko breadcrumbs; 3 tbsp butter (melted (for the panko))

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This cheesy mashed potato casserole is my favorite new addition to my holiday spread. It’s got creamy Yukon Gold mashed potatoes, crispy bacon, cheddar, mozzarella, and chives, baked under a buttery panko top. It’s a 55-minute holiday side that serves 12, and you can assemble it up to 2 days ahead. And who doesn’t love cheesy potatoes?!

A cheesy mashed potato casserole with a panko topping in a white baking dish.

Table of Contents

Why This Mashed Potato Casserole Is on My Holiday Table

a girl wearing a black leather jacket holding a drink

Is it just me or are mashed potatoes the side everyone assumes will be there, but nobody actually wants to be in charge of? They’re the last thing you’re mashing while the gravy is bubbling over and the rolls are burning…same. This casserole will solve that problem!

I prep this one a couple of days before while the kitchen is quiet. That way, on the day, I give it 45 minutes on the counter and bake it in the oven while the turkey rests! It also skips the cream cheese most baked mashed potato recipes use, and you won’t miss it, promise. Yukon Golds are buttery on their own, and with sour cream, milk, and 3 cups of cheese in the mix, these come out SO creamy.

Think of it as the loaded baked potato flavor from my air fryer twice baked potatoes, scaled up for a crowd, with a crunchy top on it. YUM!

Jordan

Ingredient Notes

Here’s a brief overview of what we’ll be using to make this delicious dish. Full measurements and instructions are in the recipe card below!

A flat lay of recipe ingredients for mashed potato casserole labeled.

Yukon Gold potatoes: I love using gold potatoes because they’re naturally buttery and mash up creamy on their own.
Sour cream: A little tang that keeps all the butter and cheese from being too heavy. I recommend full-fat because it makes them extra creamy.
Cheddar and mozzarella: I tested with two cheeses on purpose! The cheddar for flavor and the mozzarella for the cheese pull. Using both is a must!
Panko breadcrumbs: I toss these with melted butter so they bake into a golden and crunchy top. This is what makes it a casserole and not just a dish of mashed potatoes.

Recipe Variations

Skip the bacon: Leave it out for a vegetarian version. Everything else stays the same.
Different cheeses: I stick with cheddar and mozzarella, but a sharp white cheddar or pepper jack should work just fine. I haven’t tried other combos, but feel free to try your faves and let me know in the comments.
Cream cheese: I haven’t tried adding cream cheese, and with Yukon Golds and sour cream you really don’t need it!
Want it with meat mixed in? That’s a little different than a TG side, but I’ve got you! My ground turkey shepherd’s pie is a full meal under a mashed potato layer.

How to Make Mashed Potato Casserole

Step 1: Boil the potatoes in generously salted water until fork-tender, about 15 to 20 minutes. Drain them well. Any water left behind ends up making the potatoes super watery, so give them a minute in the colander.

Using a masher to mash up potatoes after boiling them.

Step 2: Using a hand masher, mash the potatoes in a large mixing bowl with the softened butter and sour cream. Slowly add the milk and keep mashing until they’re smooth and creamy, then season with salt and pepper. Stop as soon as they’re smooth, because overworked potatoes turn gummy and there’s no undoing that.

Folding in the bacon, cheese, and chives into the mashed potatoes in a mixing bowl.

Step 3: Fold in the bacon, ¾ cup of the cheddar, 1 cup of the mozzarella, and half of the chives or green onion.

Mixing the panko breadcrumbs into butter before placing on the mashed potato casserole.

Step 4: Spread the mixture into a buttered 2½-quart baking dish and top with the remaining cheddar and mozzarella. Toss the panko with the melted butter.

Sprinkling panko breadcrumbs atop the shredded cheese on a mashed potato casserole.

Step 5: Sprinkle the panko mixture evenly over the top. Get it all the way to the edges so every scoop gets some crunch.

A spoon scooping a portion of mashed potato casserole out of the baking dish.

Step 6: Bake uncovered at 375°F for 20 to 25 minutes, until the panko is golden and the cheese is bubbling around the edges. Sprinkle the remaining chives or green onion over the top and serve hot.

What to Serve with Mashed Potato Casserole

I built this dish with the holiday table in mind, so serve it next to my Cajun turkey, and a few sides like my absolute favorite cornbread stuffing and the ultimate creamed corn (with a fun jalapeño twist!). When it’s all over, the leftover turkey goes into a Thanksgiving leftover pot pie the next night.

A close up photo showing a scoop of mashed potato casserole topped with cheese and panko.

Recipe Tips

Salt the water like you mean it! Add 2 to 3 generous pinches of kosher salt to the pot before the potatoes go in. It seasons the potatoes from the inside out.
Add the milk gradually and add more only if you need it. It’s a lot easier to loosen potatoes than to thicken them back up.
Use a hand masher, which gives you the most control. If you use an electric mixer, mix just until smooth, since overmixing can make the potatoes gummy.
Bake it uncovered. The potatoes are already cooked, so all the oven is doing is heating them through and crisping the top. Foil would make the topping soft, and we want it toasty!

A serving spoon resting inside of a baked mashed potato casserole.

Storage & Make-Ahead Tips

Make ahead: This mashed potato casserole can be assembled up to 2 days before you bake it. Stir in an extra ¼ cup of milk when you mash, since the potatoes firm up as they chill, then cover and refrigerate without the topping cheese and panko. Let it sit out for about 45 minutes before baking. Then, add the cheese and buttered panko and bake as directed until it’s hot and bubbly!

Cool, cover, and refrigerate leftovers for up to 3-4 days. If you’re looking for fun ways to use up leftovers, I’d pack these potatoes on this air fryer turkey sandwich! I haven’t tried freezing this one, so I can’t promise how the sour cream holds up.

Recipe FAQs

What potatoes are best for mashed potato casserole?

Yukon Golds. They’re buttery and creamy on their own, so you get a rich casserole without adding cream cheese.

Can I use leftover mashed potatoes to make this casserole?

I haven’t tried it with leftovers or store-bought mash, but it should work if the potatoes are on the creamy side. If you have a lot of leftover mash, my mashed potato cakes are where I’d send you first.

What’s the secret to a creamy potato casserole?

The trick is first in the potatoes: Yukon Golds, then the sour cream, and finally the milk added a little at a time. I really recommend a hand masher instead of a mixer too. That’s it! Overmixing is what turns creamy potatoes gummy, and these tricks prevent it!

More Holiday Side Dish Recipes

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