Leftover Baked Potato Casserole
Use up leftover baked potatoes in a casserole that feels fresh and new. Packed with all the “loaded” flavors of bacon, green onions, cheddar cheese and sour cream this is a fun way to make leftovers shine.
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One of the best kept secrets in cooking from scratch is to batch items. Make more than you need now so things are easier later.
This leftover baked potato casserole lets you do just that. Make those potatoes ahead and use them up here with flavors that don’t disappoint.
What is a leftover baked potato casserole?
A leftover baked potato casserole takes everything you might find in a loaded baked potato and turns it into an ooey, gooey, mouthwateringly delicious casserole.
The insides of baked potatoes are mashed together with cheese, butter, and sour cream and mixed with flavor boosters such as bacon and green onions. The mixture is transferred to a casserole dish, topped with more bacon, green onions, and cheese, and baked until the cheese is gooey and melty.
This casserole presents the perfect opportunity to use up leftover baked or mashed potatoes. If you don’t have those on hand, it’s totally worth it to bake some up just for the occasion.
What potato makes the best casserole?
I recommend using russet potatoes here. Other potatoes (especially fingerling potatoes) have a higher starch content and can end you with a gluey texture.
As mentioned above, it is important not to over-mash here. As you mash, the potatoes will release starch. If too much starch is released, you will be left with a gummy, gluey mess.
How should the potatoes be mashed for this casserole?
It totally depends on how you like your potatoes. I encourage you to experiment and decide which of the following works best for you.
- Rustic. Roughly cube the baked potatoes with a knife and let the mixing process leave you with larger chunks.
- Mashed but chunky. Use a hand masher and mash until you achieve the consistency you’re looking for. This is probably my favorite method.
- Smooth. Use a hand blender. Blend just until smooth (careful not to over-blend). I suggest reheating the potatoes in the oven first and then adding a bit of milk and/or butter as you blend to make the job easier.
What you’ll need for this recipe:
Can I just leave the skins on my baked potatoes?
I actually like this casserole better with the skins. Potato skins contain a handful of beneficial vitamins and minerals and pack a hearty punch of fiber. Plus I think they add a nice, rustic quality to the dish.
They are optional though. Do as ‘ya please.
Flavor variation ideas
Potatoes make such a great canvas for a wide variety of flavors. Cheddar, bacon, and green onions are a great way to go but here are a few other fun additions and alternatives.
- Ranch dressing mix. Buy it at the store or make your own and mix it in with the potatoes. If you choose to use a store-bought product, try to select one with lower salt and MSG content.
- Crunch. Before baking, sprinkle Panko bread crumbs and/or some crispy fried shallots on top for added texture.
- Herbs. Try adding chives instead of (or in addition to) the green onions. Rosemary and/or thyme would work as well.
- Play with cheese. Try using a stronger flavored cheese such as pepper jack or even blue cheese in addition to or instead of the cheddar.
Adding meat to this casserole
You can easily upgrade this casserole from a tasty side to a hearty entree. Just add cooked meat to the top of the loaded potatoes, sprinkle with cheese, and bake.
I love incorporating leftover turkey around the holidays but chicken or BBQ pulled pork would work as well. You could even add cooked and drained ground beef as a layer underneath the potatoes for a spin on shepherd’s pie.
How to assemble leftover baked potato casserole
Scoop the insides of cooked and cooled baked potatoes into a bowl.
Add softened butter, milk, salt and pepper and mash the potatoes to your desired consistency. If your butter is too cold, warm everything in the microwave a few seconds to make mixing easier.
Add sour cream and most of the remaining toppings, leaving back some bacon, green onions and cheese for the top. Taste the potatoes to see if they need more salt.
Transfer the potatoes to a 7×11 or similar size baking dish. And 8×8 will work but be thicker. A 9×13 will be thinner. You’ll need to adjust the cooking times longer or shorter depending on your dish size.
Can you make baked potato casserole ahead of time?
This is a great make-ahead recipe! Assemble the casserole, cover the baking dish with saran wrap, and store it in the refrigerator for up to 3 days.
When you are ready to serve, pop it in the cold oven as it preheats to 350 degrees F and bake until the cheese is melty.
Can leftover mashed potato casserole be frozen?
Absolutely. Allow the casserole to cool to room temperature before wrapping the baking dish in a double layer of plastic wrap followed by a layer of aluminum foil. Store it in the freezer for up to 3 months.
When it comes time to reheat, allow the dish to thaw in the refrigerator overnight. Unwrap the thawed casserole and pop it in the oven at 350 degrees F until heated through.
What to serve with leftover baked potato casserole
This hearty dish plays beautifully with enumerable entrees and side dishes. Here are some of my favorite things to serve it with.
- Apple cider pork chops
- Vinegar-brined grilled chicken
- Air fryer salmon
- Orange ginger roasted asparagus
- Brown butter Brussels sprouts
Leftover Baked Potato Casserole
Ingredients
- 8 medium russet potatoes about 8 ounces each
- 1/2 cup butter 1 stick, softened
- 2/3 cup cultured sour cream
- 2/3 cup milk
- 1 teaspoon sea salt Celtic sea salt is best
- 3/4 teaspoon pepper
- 10 bacon strips uncured is best, cooked and crumbled
- 2 cups shredded aged cheddar cheese do not use pre-shredded cheese
- ¼ cup chopped green onions
Instructions
If you need to bake potatoes first:
- Preheat the oven to 425 degrees.
- Scrub potatoes and poke several times with a fork.
- Bake until tender, 45-60 minutes. You can also air fry them if you’d like to.
- Remove the potatoes from the oven and reduce the heat to 350.
- When potatoes are cool enough to handle each one in half down the length.
If you have leftover potatoes:
- Using a spoon, scoop out the pulp and add it to a large bowl. You can throw away the skins or chop them small and throw them in too.
- Using a fork or hand masher, mash the potatoes with the butter. Stir in the sour cream, milk, salt, and pepper.
- Save ¼ cup of the bacon mixture for topping but add the rest to the potatoes. Add in 1 cup of cheese and half the green onions and fold gently to combine. Don’t over mix or the potatoes may get gluey.
- Transfer the potatoes to a lightly greased 11×7 baking dish. Add the remaining bacon, cheese and green onions on top and bake until the cheese melts and everything is heated through 22-27 minutes.
Could you use this as part of a shepherds pie? I have a lot of leftover baked potatoes/home friends and left over beef – wondering if I could do a layer of beef below the potatoes and maybe some veggies on top!
Yes Nicola I think that would be really good!
Just wondering why you can’t use already shredded cheese–I’m sure there’s an obvious reason that I’m just not seeing! This sounds yummy and I have potatoes left from a potato bar I provided today, so I want something different!
Hey Susan, pre shredded bagged cheese is coated in an anti caking agent called cellulose that when melted can cause the cheese to become gluey or not melt at all. I just gave up on bagged cheeses a long time ago because the melting issues were getting worse and worse and just grate it from a block. –Rachel
Just wondering… at what temperature do you bake the final 22-27 minutes? At 350 or 425??
It’s 350 for that Carol. 425 was only for baking the potatoes, then you reduce the heat and assemble the recipe and finish baking at the lower temperature. –Rachel