Easy Twice Baked Mashed Potato Casserole Recipe

8 servings
1 hr 15 min

There is nothing more delicious than a twice-baked potato! But they sure do take quite a bit of time and effort. But not anymore! This Easy Twice Baked Mashed Potato Casserole Recipe has all the awesome parts of twice-baked potatoes without ever having to re-stuff the potato skins! And you can make it ahead of time!

Easy Twice Baked Mashed Potato Casserole process photo showing the finished casserole baked and out of the oven.

I adore a twice-baked potato! What I do not adore is having to be so careful emptying the potato skins and then having to refill the potato skills to give them a second bake in the oven. I came up with this great recipe to give me the very best of both worlds! It’s still the amazing filling that I put in my twice-baked potatoes… but it’s in a mashed potato casserole form! Way less work for all the same delicious flavor! This is the perfect side dish for an everyday weeknight dinner or to serve at your holiday meals! What we have here is essentially a twice-baked mashed potatoes recipe served as a casserole. This is one of my favorite recipes of all time. Are you ready? Here we go!

Ingredients for Easy Twice Baked Mashed Potato Casserole laid out on stove, including potatoes, bell peppers, onions, cheese, butter, sour cream and heavy cream.
Ingredients:


  • 5 JUMBO Russet Potatoes, or 7-10 medium-sized potatoes – Whatever you have on hand will work. Don’t go buy jumbo potatoes if you have smaller ones you can use.


  • 3 bell peppers, green, red and yellow – Again, whatever you have on hand will totally work. I do think you need at least one of the three peppers to be green to keep the flavors balanced. Red, orange and yellow peppers are much sweeter, while the green is less so. It makes a great combination!


  • 2 onions – I use sweet yellow onions, but any onions are totally fine, except green onions. You can add some green onions as a garnish if you’d like, but you really need the chopped-up onion in the mix.


  • 2 cups shredded sharp cheddar – I like to take a little help from the grocery store and just buy already shredded cheese. One bag is usually 2 exact cups!


  • 1 cup sour cream – Any kind will do – full fat, reduced fat or even fat-free is fine. It’s the most delicious with the full-fat sour cream though!


  • 1/2 cup heavy cream – This is a lot of potatoes, so don’t panic. And the heavy cream lends an amazing decadence to this dish!


  • 1 stick unsalted butter – Yes. An entire stick of butter. Again, this feeds 12ish people! That’s less than a tablespoon per serving!


  • Salt – 1 Tablespoon, or to taste


  • Ground Black Pepper – 1 teaspoon, or to taste


Cooking Instructions:


Step 1:


Wash and dry your potatoes. Depending on how much time you have, you can either bake potatoes in the oven until they are done or you can place potatoes in the microwave and cook them until they are cooked through. Let the potatoes cool so they are easier to handle.

(To microwave, I just poke a few holes in the potatoes with a fork, place them on a paper towel and microwave them in 5-minute increments, turning them every 5 minutes, until they are done. Usually 10-15 minutes)

Easy Twice Baked Mashed Potato Casserole process photo with 5 jumbo russet potatoes on a cutting board

Step 2:


While the potatoes are cooking, chop your onions and bell peppers into small pieces and sauté them in a large skillet with 2 Tablespoons of butter. I like to start them over high heat and then move down to medium heat so they have a little golden color to them. Add some salt(maybe a teaspoon salt) and pepper (not all!) to the veggies as they are cooking. I cook them for 8-10 minutes over medium heat until they have a little bit of a golden color and they are softened.

Easy Twice Baked Mashed Potato Casserole process photo with peppers and onions cooking in a large skillet

Step 3:


Heat oven to 400*.


Step 4:


Once potatoes are cool enough to handle, cut in half and scoop out the insides with a spoon into a large bowl. Discard skins. (If you like skins, feel free to mix some little pieces of skin into the potatoes).


Step 5:


With a potato masher (no need for a hand mixer — we do want a few little lumps for texture!), or even a fork, mash potatoes together in the mixing bowl until there are very few lumps.

Easy Twice Baked Mashed Potato Casserole process photo including the bowl of peeled baked potatoes broken up into small pieces

Step 6:


Add in butter, sour cream, and heavy cream and mix together until the potato mixture is the consistency of thick mashed potatoes. Add more of each ingredient or just the cream if you need to thin the mixture out a little.

Easy Twice Baked Mashed Potato Casserole process photo with cooked potatoes in a bowl with sour cream added but not yet mixed in.
Easy Twice Baked Mashed Potato Casserole process photo with the baked potatoes whipped with butter, sour cream and heavy cream.

Step 7:


Add the contents of the skillet pan with peppers, onions, and butter into the large bowl with the mashed potatoes. Mix well. Test for taste and adjust salt and pepper at this point. I always end up adding a little more salt and pepper. It’s a lot of potatoes and you want it seasoned really well! Just add the salt slowly and adjust. You don’t want to over-salt them!

Easy Twice Baked Mashed Potato Casserole process photo with large blue bowl of mashed potatoes with cooked peppers and onions on top of the mashed potatoes
Easy Twice Baked Mashed Potato Casserole process photo showing the potato mixture with the pepper and onion mixture all combined and ready to go.

Step 8:


Pour the potato mixture into a 9×13 buttered baking dish and spread evenly throughout the dish.


CAUTION: Make-Ahead or Actual Time


From here you have 2 options. If you are going to bake and eat the casserole immediately, then go on to step 8. If you are going to make the casserole ahead of time, skip to the make-ahead steps, starting with step 11.


Step 9:


If baking immediately, then sprinkle the mashed potato mixture with all of the cheddar cheese on top of the casserole, with the cheese sprinkled evenly over the entire top of the casserole.

Easy Twice Baked Mashed Potato Casserole process photo showing the mashed potato casserole in a glass 9x13 baking dish, covered in shredded cheese and ready to go in the oven.

Step 10:


Bake for 20-30 minutes at 400* until the cheese is melted and is brown and bubbly AND the potatoes are warmed through. Serve immediately.

Easy Twice Baked Mashed Potato Casserole process photo showing the finished casserole baked and out of the oven with the entire dish visable.
Make-Ahead Instructions:


MAKE AHEAD: STEP 11:


If you are like me and like to be ahead as much as possible when you are cooking, you can make this casserole up to two days before you actually intend to serve the dish. Just keep it tightly covered in the refrigerator. When you are ready to bake, let the cold dish of potatoes warm up at room temperature for 20-30 minutes, and then put it in the 350* oven for about forty-five minutes (you are now heating COLD potatoes, so it will take longer). DO NOT ADD THE CHEESE ON TOP FOR THIS STEP.


MAKE-AHEAD STEP 12:


After 45 minutes, turn the oven up to 400* and add the 2 cups of cheese on top. Bake for an additional 15-20 minutes until the cheese is golden and bubbly on top of the casserole.


Recommended Equipment:


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  • 9×13 baking casserole dish – I have this dish and I adore it because it comes with a lid that fits it. No more fooling with aluminum foil or plastic wrap! Plus it keeps the smells of your dish inside the dish and not in your refrigerator as foil and plastic wrap do!
  • Potato Masher – This is the one I use time and time again. I love anything that’s the OXO Good Grips brand, and this potato masher is no different!
  • Large non-stick skillet – I like this one because it comes with a lid. If I’m going to buy a pan or pot I like to have as many options to use it as possible!
  • Oven Mitts – This is a heavy and hot dish! Make sure you have good oven mitts to protect your hands!
  • Table Serving Trivet – This dish is HOT and will stay hot. Make sure you put it on top of something to protect your countertop or table!
  • Santoku Knife – You don’t have to go out and buy a nice knife. BUT, if you were in the market for a knife, this is the one I couldn’t do without, and the one I go for time and time again. It’s wonderfully and beautifully made. I’ve had this knife for over 10 years and it’s my favorite thing in my entire kitchen. You truly do get what you pay for in knives. These are made in Germany but are widely sold in the United States now. You can go way higher in quality as well, this is just a starting point.
  • Cheese Grater – Quick secret? I hate grating cheese. But freshly grated cheese is SO good. And I really don’t like washing a cheese grater. HOWEVER, I have found the solution to this dilemma! I do love this cheese grater. It folds flat, comes apart, and is dishwasher safe. Oxo Good Grips for the win!


Kitchen Tips and Tricks:


I use kosher salt. I think it has a wonderful flavor, and unless I’m making something sweet, I almost exclusively use kosher salt in my recipes.


Substitutions in Easy Twice Baked Mashed Potato Casserole Recipe:


Onions


Could you use green onions instead of yellow, white, or red onions? You technically could. But, green onions are not as potent as yellow, white, and red. So you wouldn’t get nearly the onion flavor in this casserole without them. But, if you just love a green onion go right ahead! No problem! Or you could sprinkle them (or just some fresh chives!) on top for a garnish and that would be delicious too. That’s the best of both worlds!


Potatoes:


I prefer the ever-durable russet potatoes for this dish. They really are the best potatoes for it. But if you prefer red potatoes or Yukon Gold potatoes, you go right ahead and use those instead. It’s totally up to you and would be delicious with any kind of potatoes!


Heavy Cream


If you just can’t get on board with the heavy cream, whole milk or half and half would work and would only sacrifice a little bit of the flavor and decadence.


Cheeses:


Want to give the potatoes alternate flavors? Try different cheeses too! This casserole with parmesan cheese would be delicious! Add some smoked gouda for a totally different take on flavors! Want spicy? Try pepper-jack cheese!


Additional Add-Ins:


You can mix and match as many ingredients as you would like in this recipe. It’s merely a framework. This is how my family likes it, but go for how your family might like it! Add in some cooked crispy bacon! It’s delightful with chopped and sautéed mushrooms added in as well. Green onions on top for garnish are also delicious! Hide some more veggies in there if you want! the sky is the limit!


Serving Suggestions:


This casserole is one of our favorite sides at our house. It’s great the night you make it and the leftovers are equally delicious the second time you have them too! We love it on the side of steaks or chicken. It’s also perfect for big holiday meals, especially since it can be made ahead of time and baked at the last minute! It’s casual enough for some grilled chicken or fancy enough for Christmas dinner.

This also makes awesome potato pancakes and incredible gnocchi if you want to get really creative with your leftovers!!


How to store Easy Twice Baked Mashed Potato Casserole Recipe:


You want to store leftovers of this dish in the refrigerator for 4-5 days, either covered in plastic wrap tightly, or in a casserole dish with a tightly fitting lid.

Need a little help with how long your leftovers stay good in the fridge? Check out this complete guide!


Frequently Asked Questions


Can I freeze this casserole before I bake it?

You can! Just don’t put the cheese on top yet! Generally, mashed potatoes don’t do so swell freezing and then de-thawing, but this potato casserole recipe has enough butter and sour cream and veggies that it will freeze beautifully! I would advocate letting it thaw in the fridge for a day before baking it so that it has time to de-thaw before you bake it.

Can I freeze the leftovers of this casserole?

You can. BUT — it doesn’t come out nearly as well once the entire casserole has been baked already. If you are going that route, I’d take the layer of cooked cheese off the top and freeze the leftovers. When you want to use them, that them completely and heat back up in the oven, and in the last 15 minutes of cooking, add a fresh batch of shredded cheese to the casserole.

I don’t like sour cream – what can I substitute?

I’ll tell ya – I don’t like sour cream either. But when it’s mixed in with all the other ingredients, you really don’t taste it. It just gives the mixture that creamy, slightly edgy flavor. But if it’s truly a no-go for you — you can totally just add in 8 ounces of cream cheese instead. It’ll be DELICIOUS that way too.

Can I leave out the bell peppers and onions?

You can if you don’t like them! You can make this your own! If you don’t like the bell peppers and onions, just omit that part of the recipe. Try adding in some delicious cooked bacon or mushrooms instead! Or leave it plain and have cheesy mashed potato casserole. It’s potatoes, you can’t go wrong. They will always be delicious.

This recipe makes way more than I need – how do I reduce the recipe?

This recipe does make a big 9×13 casserole. I love the leftovers of this casserole and I usually enjoy them for lunch for a few days after we have it. There’s a ton you can do with the leftovers as well (think potato cakes and gnocchi!). But if it’s just way more than you need, just cut the recipe down by half, or even by two-thirds to make a smaller amount of potatoes.

Easy Twice Baked Mashed Potato Casserole process photo showing a close up of the finished dish with the melted cheese on top.
Wrap Up – Easy Twice Baked Mashed Potato Casserole Recipe


I’ll tell you, the flavor of loaded potatoes in a casserole is so delicious it could bring a tear to the eye. It’s a favorite side dish at our house and it comes out perfectly every time. And as a mom that’s busy, I love a tried and true recipe I can depend on for fancy times or for casual dinners. I love that this recipe can be modified in so many ways also! It’s so versatile! Change it to make it however you’ll like it and let me know what you do! I want to hear all the variations!! Easy Twice-Baked Mashed Potato Casserole Recipe will not disappoint!


Related Recipes:


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Easy Twice Baked Mashed Potato Casserole process photo showing the finished casserole baked and out of the oven with title across the picture.
Easy Twice Baked Mashed Potato Casserole Recipe
Recipe details
  • 8  servings
  • Prep time: 45 Minutes Cook time: 30 Minutes Total time: 1 hr 15 min
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Ingredients

  • 5 Jumbo Russet Potatoes
  • 3 large bell peppers I use a red, yellow and green pepper.
  • 2 large yellow onions
  • 2 cups sharp cheddar shredded
  • 1 cup sour cream
  • 1/2 cup heavy cream
  • 1/2 cup unsalted butter 1 stick (U.S. measurements)
  • 1 Tablespoon salt or to taste
  • 1 teaspoon ground black pepper
Instructions

1. Wash and dry your potatoes. Depending on how much time you have, you can either bake potatoes in the oven until they are done or you can place potatoes in the microwave and cook them until they are cooked through. Let the potatoes cool so they are easier to handle.5 Jumbo Russet Potatoes
2. While the potatoes are cooking, chop your onions and bell peppers into small pieces and sauté them in a large skillet with 2 Tablespoons butter. I like to start them over high heat and then move down to medium heat. I like them to have a little golden color to them. Add some salt(maybe a teaspoon salt) and pepper (not all!) to the veggies as they are cooking. I cook them for 8-10 minutes over medium heat until they have a little bit of a golden color and they are softened.3 large bell peppers, 2 large yellow onions
3. Heat oven to 400°.
4. Once potatoes are cool enough to handle, cut in half and scoop out the insides with a spoon into a large bowl. Discard skins. (If you like skins, feel free to mix some little pieces of skin into the potatoes).5 Jumbo Russet Potatoes
5. With a potato masher (no need for a hand mixer — we do want a few little lumps for texture!), or even a fork, mash potatoes together in the mixing bowl until there are very few lumps.5 Jumbo Russet Potatoes
6. Add in butter, sour cream and heavy cream and mix together until the potato mixture is the consistency of thick mashed potatoes. Add more of each ingredient or just the cream if you need to thin the mixture out a little.1 cup sour cream, ½ cup unsalted butter, ½ cup heavy cream
7. Add the contents of the skillet pan with peppers, onions and butter into the large bowl with the mashed potatoes. Mix well. Test for taste and adjust salt and pepper at this point. I always end up adding a little more salt and pepper. It's a lot of potatoes and you want it seasoned really well! Just add the salt slowly and adjust. You don't want to over salt them!3 large bell peppers, 2 large yellow onions, 1 Tablespoon salt, 1 teaspoon ground black pepper
8. Pour the potato mixture into a 9Ă—13 buttered baking dish and spread evenly throughout the dish.
9. If baking immediately, then sprinkle the mashed potato mixture with all of the cheddar cheese on top of the casserole, with the cheese sprinkled evenly over the entire top of the casserole.2 cups sharp cheddar
10. Bake for 20-30 minutes at 400* until the cheese is melted and is brown and bubbly AND the potatoes are warmed through. Serve immediately.
Make Ahead Instructions:
11. If you are like me and like to be ahead as much as possible when you are cooking, you can make this casserole up to two days before you actually intend to serve the dish. Just keep it tightly covered in the refrigerator. When you are ready to bake, let the warm up at room temperature for 20-30 minutes, and then put it in the 350* oven for about forty-five minutes (you are now heating COLD potatoes, so it will take longer). DO NOT ADD THE CHEESE ON TOP FOR THIS STEP.
12. After 45 minutes, turn the oven up to 400* and add the 2 cups of cheese on top. Bake for an additional 20 minutes until the cheese is golden and bubbly on top of the casserole.
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Comments
  • Erin Erin on Dec 26, 2022

    Serving in the potato is a visual thing. Flavor is not all in the mouth.

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