I’m excited to share my cheesy mashed potato casserole recipe with you. This dish transforms instant mashed potato pouches into a delicious, creamy, and crunchy side that will be a hit at any meal.
Level: Easy
Total Time: 45 minutes
Prep Time: 15 minutes
Cook Time: 30 minutes
Yield: 8 servings
I love making cheesy mashed potato casserole because it’s simple, satisfying, and full of comforting flavors. With just a few basic ingredients and a little bit of prep work, you can create a casserole that’s creamy on the inside and has a delightful crunchy topping. Whether you’re serving it at a family dinner or a casual get-together, this casserole is sure to impress.
Description
For this recipe, I use two pouches of instant mashed potatoes to keep things quick and easy. I start by sautéing green onions and chopped yellow bell pepper in butter until they are soft and fragrant. Then, I bring together hot water, whole milk, and butter, and stir in the instant mashed potato pouches with their seasonings. I beat the mixture until it’s smooth and fluffy. Next, I layer the mashed potatoes, the sautéed vegetables, and shredded cheddar cheese in an oiled casserole dish. The layering process creates a mix of creamy and cheesy textures with a crispy, bubbly top when baked. This dish is perfect as a side for any main course and makes eight generous servings.
Ingredients
- 1/4 cup plus 2 teaspoons unsalted butter
- 1/2 cup sliced green onions
- 1 cup chopped yellow bell pepper
- 3 cups hot water
- 1 cup whole milk
- 7 oz box roasted garlic instant mashed potatoes (use 2 pouches)
- 1 1/2 cups shredded cheddar cheese

Directions
- Preheat and Prepare:
- Preheat your oven to 350°F.
- Spray a 2-quart casserole dish with nonstick cooking spray.
- Sauté Vegetables:
- In a skillet over medium heat, melt 2 teaspoons of butter.
- Add the sliced green onions and chopped yellow bell pepper.
- Sauté for about 5 minutes, until the vegetables are tender. Set aside.
- Prepare Mashed Potatoes:
- In a saucepan over medium heat, combine the hot water, whole milk, and 1/4 cup butter.
- Bring the mixture to a boil.
- Stir in both pouches of the instant mashed potatoes along with their seasonings.
- Beat the mixture with a fork until smooth and fluffy.
- Layer the Casserole:
- Spread 1 1/3 cups of the mashed potatoes in the bottom of the casserole dish.
- Evenly distribute half of the sautéed vegetable mixture over the mashed potatoes.
- Sprinkle 3/4 cup of shredded cheddar cheese over the vegetables.
- Layer another 1 1/3 cups of mashed potatoes on top, followed by the remaining vegetable mixture.
- Top with the remaining mashed potatoes and sprinkle the final 3/4 cup of cheddar cheese evenly on top.
- Bake:
- Place the casserole in the preheated oven and bake for 30 minutes or until the potatoes are piping hot and the cheese is bubbly and slightly golden.
- Serve:
- Remove the casserole from the oven and serve hot.
Process Details
- Vegetable Sauté: Sautéing the green onions and bell pepper brings out their natural sweetness and adds a fresh crunch to the dish.
- Fluffy Mashed Potatoes: Beating the instant mashed potatoes after adding hot water and milk ensures a smooth, creamy texture that binds well with the layers.
- Layering Technique: Alternating layers of mashed potatoes, vegetables, and cheese creates a delightful mix of textures in every bite.
Tips for Success
- Mix Well: Make sure to beat the mashed potatoes thoroughly to eliminate any lumps for a smoother casserole.
- Even Layers: Spread each layer evenly to ensure a consistent flavor and texture throughout the dish.
- Cheese Options: Feel free to experiment with different cheeses like Monterey Jack or a blend of cheddar and mozzarella for extra creaminess.
- Make Ahead: You can prepare the layers ahead of time and refrigerate the casserole for up to 24 hours before baking; just add a few extra minutes to the baking time if needed.
Serving Ideas
- Side Dish: This casserole is a great side for roasted chicken, grilled steak, or a hearty vegetable stew.
- Potluck Favorite: It makes an excellent addition to potluck dinners or family gatherings where you want to impress with minimal effort.
- Comfort Food: Serve it on a cold day as a warm, comforting dish that will keep everyone satisfied.
Nutrition Info (Approximate per Serving)
- Calories: 300–350
- Fat: 15–18 grams
- Carbohydrates: 30–35 grams
- Protein: 10–12 grams
I truly enjoy making cheesy mashed potato casserole because it combines convenience with rich, comforting flavors. The creamy texture, paired with the crunchy, bubbly cheese topping, makes it a standout side dish. I hope you give this recipe a try and enjoy it as much as I do. Let me know your thoughts and any feedback once you’ve made it!