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This twice baked potato casserole recipe has all the flavor of traditional twice baked potatoes, but in casserole form! This dish is easy to make (or make ahead), and you can even use leftover mashed potatoes to make it.
Twice baked potatoes are a classic appetizer. They’re creamy, crispy, salty, and cheesy, all in a perfect portable finger food. Here we take that crowd-pleasing appetizer and turn it into a side dish everyone loves!
Double baked mashed potatoes in casserole form have the same flavors and textures as traditional twice baked potatoes. In this recipe, hearty potatoes are mashed with aromatic sautéed buttery garlic and onion, cream, and cheese. Then topped with more cheese!
And because we’re making these into loaded twice baked mashed potato casserole, we add bacon on top. The finishing touch is a green herb for a pop of color; you can use parsley, or to with chives for a mild onion flavor.
Because we’re transforming twice baked potatoes into a casserole form, it almost reminds me of baked macaroni and cheese.
This cozy side dish is a great accompaniment to any hearty meal. And if you’re looking for a new Thanksgiving, Christmas, or New Year’s Eve side dish to try, give this one a go!
You can make this ahead of time, which is great for meal prep and if you want to make it for the holidays, it helps to reduce the workload for holiday meals.
And if you don’t make this as a side dish for Thanksgiving dinner, keep it in mind as a recipe for your leftover mashed potatoes. This is a great use for them because it’s different enough that no one would guess its leftovers!
Cheesy Twice Baked Potato Casserole Recipe Ingredients and Substitutions
In this section I explain the ingredients and give substitution ideas. For the full recipe (including ingredient amounts), see the recipe card below.
- Yukon Gold potatoes – for this recipe, you can use whatever your favorite type of potato is for making mashed potatoes; I like using Yukon gold potatoes because they mash up smooth and creamy, they have a pretty golden color, and their skin is thin so you don’t have to peel them first
- Unsalted butter – for richness; we use this to sauté the onion and garlic
- Onion and garlic – for depth of flavor and aroma; if you don’t have fresh onion and garlic on hand, you can substitute with 2 teaspoons onion powder and 1 teaspoon garlic powder
- Milk – I use whole milk, but you can use any type of milk you like in your mashed potatoes
- Sour cream – sour cream is a classic ingredient in twice baked potatoes, and it adds creamy texture and a subtle tangy flavor here, which is great for balance; however, if sour cream isn’t your thing, feel free to omit it and use 2 ounces of cream cheese instead
- Salt and black pepper – these simple seasonings add a ton of flavor
- Shredded cheddar – I like a mix of yellow and white cheddar here, but you can use whatever you like
- Beef bacon – this is a topping that adds crispy texture and salty flavor; you can omit it if you prefer, or use any type of bacon you like
- Fresh parsley – or fresh chives (for garnish)
How to Make Twice Baked Mashed Potato Casserole
Step 1: Chop and Boil the Potatoes
- Wash the potatoes and cut them into cubes. (If you’re using Yukon Gold potatoes or another type of yellow potato, there’s no need to peel them.)
- Add the potato cubes to a 3-quart saucepan and add enough cold water to cover the potato by 2 inches.
- Bring to a boil, then turn the heat down slightly (so it doesn’t boil over), and boil vigorously until the potatoes are tender, about 15 to 20 minutes.
- Drain.
To Bake the Potatoes Instead of Boiling Them for Mashed Potatoes
Scrub the potatoes, pat them dry, and poke each potato a few times with a paring knife or the tines of a fork. Put the potatoes on a foil-lined baking tray and bake in a preheated 400F oven until a paring knife slides in and out of the center of a potato without resistance, about 1 hour.
Once they’re cool enough to handle, slice each potato in half, scoop out the flesh, and mash it as directed in this recipe. (Don’t add the potato skins if you bake the potatoes because the skins get hard during baking.)
Step 2: Sauté the Onion and Garlic and Mash the Potatoes
- While the potatoes are cooking, cook the onion. To do so, add the butter to a small skillet over medium heat. Once it starts to melt, add the onion and cook until it’s starting to soften but not brown, about 2 to 3 minutes, stirring frequently. Stir in the garlic and cook 1 minute more, stirring constantly. Remove from the heat.
- Once the potatoes are drained, add them to a large bowl with the onion/garlic/butter mixture (make sure you scrape in all the butter!), milk, sour cream, salt, and black pepper. Use a potato masher to mash everything together (it doesn’t have to be perfectly smooth, a few lumps are fine).
- Add 3/4 cup shredded cheese.
- Stir just until combined.
Step 3: Assemble the Casserole and Bake
- Transfer the potato mixture to the prepared baking dish, spread it out evenly, and sprinkle the remaining 1 cup shredded cheese evenly on top. Cover with foil and bake 20 minutes.
- Remove the foil, sprinkle on the bacon, and broil a couple minutes to brown the top. Sprinkle on the fresh parsley or chives.
Storage
You can store leftover twice baked potato casserole covered in the fridge for up to 4 days.
Reheating Leftovers
If you’re heating up a single serving or two, the microwave works well.
However, if you want to reheat the entire casserole after it’s been baked, I recommend using the oven. To do so, pull the casserole out of the fridge and let it sit at room temperature for 30 minutes, and then pop it into a preheated 350F oven until warm throughout.
How to Make This Dish Ahead
You can make this recipe through Step 5 in the recipe below, cover the dish with foil, and refrigerate it for up to 2 days.
When you want to serve it, let the casserole sit for 30 minutes at room temperature, and then bake (covered) in a preheated 375F oven until warm throughout, which takes about 45 minutes. After that, continue on with Step 7 in the recipe below.
Twice Baked Potato Casserole Recipe FAQs
What Type of Potato is Good for Mashed Potatoes?
That depends on how you like your mashed potatoes!
If soft, fluffy mashed potatoes are your thing, then starchy potatoes (such as Russet) should be your go-to.
And if you prefer rich, creamy, and more decadent mashed potatoes, then you’ll want to opt for semi-starchy, semi-waxy yellow potatoes (like Yukon Gold).
I don’t recommend using waxy potatoes (such as red potatoes and white potatoes) for making mashed potatoes because they have the tendency to be gummy.
How Do You Know When Potatoes Are Ready to Mash?
When you’re boiling potatoes to make mashed potatoes, you can use a paring knife or a fork to tell when they’re done. Pierce a piece of potato with a fork or knife and if it goes in with no resistance and slides right out, your potatoes are ready.
It generally takes about 15 to 20 minutes of boiling to get cubed potatoes to the point where they’re ready to mash.
Can You Make Mashed Potatoes Ahead of Time?
Yes! Mashed potatoes are a great make ahead side dish because if you reheat them correctly, you’ll never know they weren’t made fresh.
You can reheat mashed potatoes in the microwave, on the stovetop, or covered in the oven (at 350F). The main thing to remember when reheating leftover mashed potatoes is that you’ll need to help prevent them from drying out! You’ll need to add a splash of milk or cream, and you’ll want to stir periodically.
You can make the mashed potatoes for this recipe up to 4 days ahead of time before making this casserole!
How to Rehat Mashed Potatoes in the Microwave
Use a microwave-safe bowl, spread the mashed potatoes out as evenly as you can, and place a slightly damp paper towel on top of the potatoes. Microwave them in 1 minute intervals, stirring between each. Once the potatoes are warm, add a splash of milk or cream and stir until they’re smooth.
Why Soak Potatoes Before Cooking Mashed Potatoes?
Some mashed potato recipes instruct you to soak potatoes in cold water after they’re chopped. After soaking, the potatoes are drained, and then boiled until tender. Then they’re drained again, and finally mashed.
This is because soaking potatoes can help remove excess starch, which can cause mashed potatoes to become gummy or gluey.
However, if you use the right type of potato, I find this isn’t a problem and there’s no need to soak potatoes before making mashed potatoes.
This is why I prefer using yellow potatoes, such as Yukon Gold. They’re the perfect balance between starchy and waxy, so they’re the best of both worlds. And bonus, their skin is tender and mashes well, so you don’t have to peel the potatoes!
What Does Adding an Egg to Mashed Potatoes Do?
There are a few things that adding an egg does to mashed potatoes:
- The egg white helps the potatoes set (which can be an ace up your sleeve if you accidentally added to much milk to your mash!).
- The egg yolk adds rich flavor and creamy texture, creating a very velvety mouthfeel.
- Adding an egg also bumps up the protein.
- If you’re cooking the potatoes again (like in this twice baked mashed potato casserole), the egg will help the top brown a bit.
I didn’t add an egg to the mashed potatoes for this recipe, but feel free to add one if you want to try it! Lightly beat 1 egg and mash it into the potatoes along with the milk.
More Cheesy Side Dishes to Try
- Celery Gratin – this is quick and easy, and perfect if you want a low carb and keto side dish
- Decadent Instant Pot Mac and Cheese – the cheese blend here is incredible, and it’s made entirely in the instant pot, even the crunchy, buttery cracker topping
- Cauliflower Gratin – inspired by British cauliflower cheese, this dish is the best of both words; you’re still getting a vegetable, but it has a rich cheese sauce and crunchy topping
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Twice Baked Potato Casserole Recipe
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Ingredients
- 1 1/2 pounds Yukon Gold potatoes washed and cut into 1-inch cubes (not peeled)
- 4 tablespoons unsalted butter
- 1/3 cup diced yellow onion about 1/2 small onion
- 1 large clove garlic crushed
- 4 tablespoons whole milk
- 4 tablespoons sour cream
- 1/2 teaspoon salt
- 1/8 teaspoon black pepper
- 1 3/4 cups shredded cheddar I like a mix of yellow and white cheddar here
- 2 slices beef bacon cooked until crispy and crumbled (this is optional; you can omit it or use any type of bacon you like)
- 2 teaspoons minced fresh parsley or chives (for garnish; optional)
- Nonstick cooking spray
Instructions
- Add the potato cubes to a 3-quart saucepan and add enough cold water to cover the potato by 2 inches. Bring to a boil, then turn the heat down slightly (so it doesn’t boil over), and boil vigorously until the potatoes are very tender, about 15 to 20 minutes. Drain.
- While the potatoes are cooking, cook the onion. To do so, add the butter to a small skillet over medium heat. Once it starts to melt, add the onion and cook until it’s starting to soften but not brown, about 2 to 3 minutes, stirring frequently. Stir in the garlic and cook 1 minute more, stirring constantly. Remove from the heat.
- Once the potatoes are drained, add them to a large bowl with the onion/garlic/butter mixture (make sure you scrape in all the butter!), milk, sour cream, salt, and black pepper. Use a potato masher to mash everything together (a few lumps are fine).
- Fold 3/4 cup shredded cheese into the potato mixture.
- Lightly spray the inside of a 7 by 11-inch casserole dish (or equivalent 2.5-quart baking dish) with nonstick cooking spray. Transfer the potato mixture to the prepared baking dish, spread it out evenly, and sprinkle the remaining 1 cup shredded cheese evenly on top.
- Cover with foil and bake 20 minutes in a preheated 375F oven.
- Remove the foil, sprinkle on the bacon, and broil a couple minutes to brown the top.
- Sprinkle on the parsley or chives, and serve.
Notes
- Storage: You can store leftover twice baked potato casserole covered in the fridge for up to 4 days.
- Reheating Leftovers: If you’re heating up a single serving or two, the microwave works well. However, if you want to reheat the entire casserole after it’s been baked, I recommend using the oven. To do so, pull the casserole out of the fridge and let it sit at room temperature for 30 minutes, and then pop it into a preheated 350F oven until warm throughout.
- Make Ahead: You can make this recipe through Step 5 above, cover the dish with foil, and refrigerate for up to 2 days. When you want to serve it, let it sit for 30 minutes at room temperature, and then bake (covered) in a preheated 375F oven until warm throughout, which takes about 45 minutes. After that, continue on with Step 7 in the recipe above.
- How to Use Leftover Mashed Potatoes to Make This Recipe: You can make the mashed potatoes for this recipe up to 4 days ahead of time before making this casserole! You can either make this recipe through Step 3 above, or use any leftover mashed potatoes you have.
- When you want to make this casserole, if you want it to taste like you used freshly mashed potatoes, I recommend reheating the mashed potatoes first before you proceed with Step 4 above. You can reheat mashed potatoes in the microwave, on the stovetop, or covered in the oven (at 350F). The main thing to remember when reheating leftover mashed potatoes is that you’ll need to help prevent them from drying out! You’ll need to add a splash of milk or cream, and you’ll want to stir periodically.
- If you want to reheat leftover mashed potatoes in the microwave, use a microwave-safe bowl, spread the mashed potatoes out as evenly as you can, and place a slightly damp paper towel on top of the potatoes. Microwave them in 1 minute intervals, stirring between each. Once the potatoes are warm, add a splash of milk or cream and stir until they’re smooth.
Nutrition
Nutritional information is automatically calculated and should be used as an approximate.
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I’m the writer, recipe developer, photographer, and food stylist behind this blog. I love finding the human connection through something we all do every day: eat! Food is a common ground that we can all relate to, and our tables tell a story. It’s my goal to inspire you to get in the kitchen, try something new, and find a favorite you didn’t know you had.
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