Garlic Parmesan Mashed Potato Casserole makes the PERFECT Thanksgiving and holiday side dish! Creamy russet potatoes are cooked with garlic cloves, then mashed with butter, milk and Parmesan cheese. Top with additional Parmesan before baking to create a crispy exterior on this comforting casserole. No matter if you’re serving the family for a holiday or on a weeknight, Mashed Potato Casserole packs a flavorful punch for any meal!
Mashed Potato Casserole
The night I made this Mashed Potato Casserole for the first time, my husband declared, “I think those are the best mashed potatoes you’ve ever made.”
And y’all, this is something coming from him because the man is not really the biggest mashed potato fan.
A little backstory: He’s the great-grandson of a rice farmer, so their family always ate rice with dinner. For him to be on board with a mashed potato dish is kind of a Big Deal.
Garlic Parmesan Mashed Potatoes
These Garlic Parmesan Mashed Potatoes is my new favorite potato dish, too, because it is so very simple to make. It also packs a ton of flavor into the potatoes and works as a side dish for a weeknight meal, as well as a holiday like Thanksgiving or Christmas.
No matter when you serve this mashed potato casserole, it’s gonna be a hit!
And the best news is Garlic Parmesan Mashed Potato Casserole can and should be made in advance so you don’t have to fret about it the day of! (I’ll talk about this in a bit. Promise.)
Easy peasy, folks.
Make Ahead Mashed Potato Casserole
What is the best way to mash the potatoes?
Personally, I like to use a hand mixer to make the mashed potatoes super smooth and creamy.
The key is making sure the potatoes are soft enough that they can very easily blend them up with the other ingredients.
When the potatoes are fork tender, drain, then toss them back in the saucepan (or Dutch oven) with the butter, milk and parmesan. Start blending slowly with the hand mixer and pick up speed as the ingredients meld together. Blend until the potatoes are whipped and smooth and the perfect silky consistency.
Mashed Potato Casserole Recipes
Does this recipe use leftover mashed potatoes? Or can I substitute them in for the fresh mashed potatoes?
If you happen to have 3 lbs. of mashed potatoes leftover, absolutely! Depending on how they were made, you might need to add a little more milk, butter and parmesan. Also, garlic.
With the garlic, I suggest cooking it in a pan with some olive oil or butter before throwing it into the potatoes so it’s not completely raw.
Grocery list for Easy Potato Casserole
- russet potatoes
- unsalted butter
- whole milk
- 1parmesan cheese
- black pepper
- kosher salt
Can I make this Mashed Potato Casserole ahead of time?
YES! In fact, I advise doing this.
When we plan our dishes for Thanksgiving, my family and I try to make as many as possible in advance. Make the mashed potatoes a day or two before the big day, and transfer them into a baking dish. (You won’t cover them in cheese or bake now—that’ll come the day of!) All you’ll do now is cover them with plastic wrap, then store in the fridge.
The day of, unwrap the casserole dish, top with cheese and bake until the cheese is golden, brown, bubbly and delicious. Make ahead mashed potato casserole makes the big day SO much easier!
Can I make this casserole at home and transport it to another location without too much drama?
YES! This dish would be awesome to transport and quite easy to finish at someone else’s house.
I’d follow the instructions laid out about making the dish in advance. Bring it covered in plastic wrap, and once there, top with cheese and bake until bubbly and delicious.
I don’t like fresh garlic. Can I use granulated garlic instead?
Sure! I know fresh garlic can be a little strong for some people, so if you want to make the swap with granulated garlic, do it.
I would start with ½ teaspoon of the granulated garlic. Taste it for flavor, and add more if you want more garlic flavor.
What tools do I need to make this Garlic Parmesan Mashed Potato Casserole?
What else can I serve at a holiday or Thanksgiving gathering alongside this mashed potato casserole?
Now, who’s ready to make this life-changing, make-ahead mashed potato casserole?
Scroll on down to learn how simple it is to make…
Garlic Parmesan Mashed Potato Casserole Recipe
- 3 lbs. russet potatoes , scrubbed, peeled and diced into 1” cubes
- 5 garlic cloves , whole
- 1 teaspoon kosher salt (to season put in water for the diced potatoes)
- 4 tablespoons unsalted butter
- 1 cup whole milk
- 1 3/4 cups parmesan cheese , shredded and divided
- 1 teaspoon black pepper , freshly ground
- 1.2 teaspoon kosher salt
- Using a sharp knife, chop the scrubbed and peeled potatoes into 1” cubes.
- Fill a large saucepan or Dutch oven with water, then add the potatoes to the water. Place the garlic cloves in the water, as well.
- Season the water with a teaspoon of salt.
- On the stovetop, heat the water and potatoes over high heat and bring to a boil. Cook until the potatoes are fork tender, about 20 minutes.
- Drain the potatoes, and place back in the saucepan.
- Measure out the butter, milk and 1 cup of parmesan cheese on top of the potatoes.
- Using a hand mixer on a low speed, slowly blend the ingredients together until smooth and creamy.
- Season the potatoes with salt and pepper.
- Preheat the oven to 350°F. Spray a baking dish with nonstick cooking spray, and set aside.
- Transfer the mashed potatoes into the prepared baking dish. Sprinkle the additional ¾ cup cheese on top of the casserole.
- When the oven is preheated, transfer the casserole to the oven.
- Bake for 25 minutes, then turn up the heat to 425°F. Bake for an additional 15 minutes, or until the cheese has browned.
- Remove from the oven, and let cool slightly.
- Serve warm, and enjoy!