Use leftover mashed potatoes or make it from scratch! This easy mashed potato casserole recipe with sour cream is a keeper and will be in your family for years! It's a winning combination of minimal prep time, easy to assemble, and a rich, satisfying taste.
Mashed Potatoes are a must-have dish for most Holiday dinners, and this mashed potato casserole takes the mashed potatoes (leftover or fresh) to a different level. Layers of flavors with sour cream, sauteed bell peppers, cooked sliced potatoes, and shredded cheese seal the deal.
This casserole uses my leftover garlic mashed potatoes, and goes really well with all the other holiday sides like mushroom croissant bake, lentil shepherd's pie, and caramelized onion mac and cheese.
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✨What you'll love about this recipe?
- Great way to use leftover mashed potatoes
- Make ahead recipe - perfect for busy holiday cooking schedules
- Added flavor of peppers, onions, cheese, and sour cream to elevate the humble potato.
📋Recipe Ingredients
- Mashed Potatoes - make a fresh batch of these garlic mashed potatoes with cream cheese or use leftovers. I have not tried this recipe with instant mashed potatoes, but if that's your thing, do it!!
- Potatoes - we need cooked potatoes that will be sliced and added to the casserole as a layer. You can either boil or bake the potatoes. Russet potatoes are my favorite to use in this recipe.
- Bell Peppers - Use a mix of colored bell peppers or whatever you can find. I have used red and green bell peppers here because they look very festive.
- Cheese - I have used a mix of cheddar and Monterey jack here. Cheddar is more traditional for any type of potato casserole.
Remember to check out the recipe card below for a complete list of ingredients and quantities.
📖Substitutions, Additions and Variations
- Spicy - add chopped Serrano when sauteing the bell peppers and onions. You can also use pepper jack cheese instead of cheddar cheese.
- Instant mashed potatoes - if you don't have leftover mashed potatoes or don't want to make a fresh batch, you can use instant mashed potatoes. They're not exactly the same but they will work.
- Bacon - add crumbled crispy bacon on top after baking.
👩🍳Steps to make this recipe
Step 1: Spread a layer of mashed potatoes in a baking dish (Image 1).
Step 2: Spread a layer of sour cream and sprinkle of salt, black pepper, and garlic powder (Image 2).
Step 3: Saute some sliced bell peppers and onions in butter (Image 3).
Step 4: Layer the sauteed bell peppers and onion over the sour cream layer (Image 4).
Step 5: Slice the cooked potatoes and layer over the peppers layer. Sprinkle with seasonings (Image 5).
Step 6: Add shredded cheese (Image 6) and bake until the cheese is melted.
💡Vaishali's Tip!
- After the casserole is baked, let it sit for a few minutes before serving and digging in. This will help all the layers settle and you won't end up with a mush.
🫙Storage, freezing, and reheating instructions
Store any leftovers in an air-tight container in the refrigerator for up to 3 days. To reheat, take a serving out on a plate and microwave until heated through.
❓FAQ
Yukon gold or any yellow potatoes are my favorite for making garlic mashed potatoes. Yellow potatoes will also work for the sliced potatoes if you do not want to buy two different kinds of potatoes.
Yes, you can. Assemble everything, cover with foil, and store in the refrigerator up to two days in advance. When ready to serve, take it out of the refrigerator and proceed to bake.
Related
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If you make this recipe be sure to leave a comment and let me know how you liked it! Share it on Instagram with the hashtag #thekitchendocs or share on Facebook, too.
Love – Vaishali
Easy Mashed Potato Casserole Recipe with Sour Cream
Equipment
Ingredients
- 1 cup Leftover mashed potatoes recipe
- ¼ cup sour cream
- 1 tablespoon butter
- ½ cup thin sliced green bell pepper
- ½ cup thin sliced red bell pepper
- ½ cup sliced white or yellow onion
- 2 medium potatoes cooked
- ½ cup shredded cheese a mix of cheddar and Monterey jack
- salt, black pepper, and garlic powder to taste
- Chopped chives For garnish, optional
Instructions
- Preheat the oven to 350 degrees F or 175 degrees C. Mix 1 tablespoon salt with ¼ tablespoon each of black pepper and garlic powder. This is your seasoning blend.
- Peel and slice the cooked potatoes.
- Set a small frying on medium-high heat. Add butter and saute the bell peppers and onions until softened about 5-7 minutes. Sprinkle ¼ teaspoon of seasoning blend and mix.
- While the veggies are cooking, take your baking dish and spread a layer of mashed potatoes in it.
- Top the mashed potato layer with the sour cream and spread it evenly. Sprinkle a generous pinch of the seasoning blend you made.
- Add the sauteed peppers and onions on top of the sour cream layer and spread evenly.
- Place the sliced potatoes on top of the peppers and onions layer and sprinkle with seasoning. Add the shredded cheese on top.
- Bake for 25-30 minutes or until the cheese is melted and golden. Garnish with chopped chives.
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