Introduction

This Mashed Potato Casserole is a comforting and cheesy twist on classic mashed potatoes. Topped with crispy bacon and a blend of melted cheeses, it’s perfect for family dinners or potlucks. Easy to make ahead and bake, it delivers rich flavor and creamy texture every time.

Mashed Potato Casserole Recipe - Recipe Image

Ingredients

0.17kg (0.35 lb) potatoes (Sebago, Russet, Maris Piper, or King Edwards)
0.1 tbsp cooking or kosher salt, for cooking potatoes
0.07 cup milk (preferably full fat/whole milk)
0.07 cup extra milk, for make-ahead option only
7.5g (0.5 tbsp) unsalted butter, cut into 1cm (1/2″) cubes
0.05 cup sour cream or full fat yogurt
0.1 tsp cooking or kosher salt, or to taste
0.15 cups tightly packed freshly shredded mozzarella
0.1 cup tightly packed Red Leicester, cheddar, or other flavored cheese
20g (0.6 oz) streaky bacon, chopped
0.03 cup green onion, finely sliced

Instructions

Step 1: Cook the bacon by placing it in a cold non-stick pan over medium heat without oil. As the pan heats, the bacon fat will melt. When you see melted bacon fat, increase heat to medium-high and stir for about 3 minutes until bacon is golden. Drain on paper towels.
Step 2: Peel the potatoes and cut into 3cm (1″) chunks. Place them in a large pot and cover with water about 10cm (4″) above the potatoes. Add 1 tablespoon salt and bring to a boil over high heat. Reduce to a rapid simmer and cook for 15 minutes or until potatoes are very soft when pierced with a fork.
Step 3: Drain the potatoes well and return them to the pot. Let sit for 1 minute, shaking occasionally to evaporate excess water.
Step 4: Mash the potatoes adding milk (including the extra milk if making ahead), butter, sour cream, and 1 teaspoon salt. Mash until smooth, being careful not to use a food processor, blender, or beater to avoid gluey texture.
Step 5 (Make-ahead option): Allow mashed potatoes to cool fully on the counter, then cover tightly with cling wrap and refrigerate. Remove from fridge 2 hours before reheating to come to room temperature.
Step 6: Preheat the oven to 200°C (400°F) or 180°C fan.
Step 7: Spread the mashed potato evenly in a 2-litre (2-quart) baking dish and smooth the surface.
Step 8: Sprinkle the mozzarella and flavored cheese evenly over the potatoes, then top with the cooked bacon.
Step 9: Cover loosely with foil and bake for 20 minutes if freshly made, or 35 minutes if using the make-ahead option.
Step 10: Remove the foil and bake uncovered for an additional 10 minutes until cheese is bubbly and golden.
Step 11: Sprinkle green onion over the casserole before serving. The cheese topping keeps it warm for about 20 minutes.

Tips & Variations

Use full-fat milk and sour cream for the creamiest texture, but lighter dairy options work too.
Try different cheeses like Gruyère or smoked cheddar for varied flavors.
For extra crunch, sprinkle some breadcrumbs on top before baking uncovered.
Substitute bacon with cooked sausage or mushrooms for a vegetarian version.

Storage

Store any leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in the oven at 180°C (350°F) until warmed through, about 15-20 minutes. Avoid microwaving to retain creamy texture and crispy topping.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I make this casserole ahead of time?

Yes, you can prepare the mashed potatoes in advance, refrigerate them, and bake when ready. Just allow the casserole to come to room temperature before baking for even cooking.

What type of potatoes work best?

Starchy potatoes like Russet, Sebago, Maris Piper, or King Edwards are best as they mash smoothly and create a creamy texture without becoming gluey.

Mashed Potato Casserole Recipe

Print Recipe

★★★★★

4.7 from 136 reviews

This Mashed Potato Casserole is a comforting and cheesy dish featuring tender, creamy mashed potatoes layered with crispy bacon and melted mozzarella and cheddar cheeses. Perfect as a hearty side or a satisfying main, this recipe offers flexibility with make-ahead instructions and is finished with fresh green onions for a bright, savory touch.

Author: Kai
Prep Time: 15 minutes
Cook Time: 35 minutes
Total Time: 50 minutes
Yield: 4 servings 1x
Category: Side Dish
Method: Baking
Cuisine: American

Ingredients

Scale

Potatoes and Dairy

0.17 kg (0.35 lb) potatoes (Sebago (Aus), Russet (US), Maris Piper / King Edwards (UK))
0.1 tbsp cooking or kosher salt, for cooking potatoes
0.07 cup whole milk (preferably full fat, lite is acceptable)
0.07 cup extra milk (for make-ahead option only)
7.5 g (0.5 tbsp) unsalted butter, cut into 1 cm (1/2″) cubes
0.05 cup sour cream or full-fat yogurt
0.1 tsp cooking or kosher salt, or to taste

Cheese and Toppings

0.15 cups (tightly packed) shredded mozzarella cheese
0.1 cup (tightly packed) shredded Red Leicester, cheddar, or other flavored cheese
20 g (0.6 oz) streaky bacon, chopped
0.03 cup finely sliced green onion

Instructions

Cook bacon: Place chopped bacon in a cold non-stick pan over medium heat without adding oil. As the pan heats up, the bacon fat will render. Once you see the melted fat, increase heat to medium-high and stir continuously for about 3 minutes or until the bacon turns golden and crispy. Remove the bacon and drain on paper towels to remove excess fat.
Prepare potatoes: Peel the potatoes and cut them into 3 cm (1 inch) chunks. Place them in a large pot and cover with water so it is 10 cm (4 inches) above the potatoes. Add 1 tablespoon of salt to the water.
Boil potatoes: Bring the pot to a boil over high heat, then reduce to a rapid simmer. Cook the potatoes for about 15 minutes or until they are very soft and easily pierced with a fork. Drain the potatoes well and return them to the pot. Leave them for 1 minute, shaking occasionally to help evaporate excess water.
Mash potatoes: Add the milk (include the extra milk if using the make-ahead option), butter cubes, sour cream, and 1 teaspoon salt to the potatoes. Mash thoroughly using a hand masher until smooth. Avoid using a food processor, blender, or electric beater as this can make the potatoes gluey.
Make-ahead instructions: If you want to prepare this ahead of time, allow the mashed potatoes to cool completely at room temperature. Cover tightly with cling film and refrigerate. When ready to bake, remove from the fridge and sit on the counter for 2 hours to come to room temperature before proceeding.
Assemble casserole: Preheat the oven to 200°C (400°F) or 180°C fan. Transfer the mashed potatoes to a 2 litre (2 quart) baking dish and smooth the surface evenly. Sprinkle the shredded mozzarella and cheddar (or other flavoured cheese) evenly over the top, followed by the cooked bacon.
Bake covered: Loosely cover the dish with foil. Bake for 20 minutes if freshly made or 35 minutes if using the make-ahead option.
Bake uncovered: Remove the foil and bake for an additional 10 minutes until the cheeses are bubbly and golden brown on top.
Serve: Sprinkle the finely sliced green onions over the casserole and serve immediately. The dish retains heat well for about 20 minutes due to the protective cheese layer.

Notes

Choose starchy potatoes like Russet, Sebago, Maris Piper, or King Edward for the best mash texture.
Use full-fat milk and sour cream for creamier, richer mashed potatoes.
If making ahead, the extra 0.07 cup milk is added during mashing to keep the potatoes creamy after refrigeration.
Bacon adds a salty, crispy contrast; streaky bacon is recommended for flavor and fat content.
The baking dish should be around 2 liters (2 quarts) to accommodate the potato volume comfortably.
Do not overmix potatoes with electric appliances to avoid gummy texture.

Keywords: mashed potatoes, potato casserole, cheesy potato bake, bacon mashed potatoes, comfort food, side dish