Creamy Cheesy Potato Casserole

This cheesy potato casserole is the kind of side dish that disappears fast at any dinner table. Tender chunks of potato bake in a rich, garlicky cheddar sauce, then finish with a buttery, crunchy topping.

It’s a from-scratch version that skips the canned soup, using real cheese and a simple roux for a sauce that stays creamy from oven to plate.

What Makes This Casserole So Good

I keep coming back to this recipe because the sauce never breaks or turns grainy, even after baking. The sour cream adds a little tang and the sharp cheddar gives it a real cheese flavor, not just a vague creaminess.

The topping is just crushed cornflakes tossed with melted butter, but it bakes into this crisp, golden layer that contrasts with the soft potatoes underneath. I’ve made it for holidays, potlucks, and random weeknights, and it always gets scraped clean.

Ingredients

• 3 lbs russet potatoes, peeled and diced into 1/2-inch cubes: starchy potatoes soak up the sauce best.
• 3 tbsp unsalted butter: for the roux.
• 3 tbsp all-purpose flour: to thicken the sauce.
• 2 cups whole milk: warms up smoothly without scorching; 2% works too.
• 1 tsp kosher salt: adjust to taste if your cheese is salty.
• 1/2 tsp black pepper
• 1/2 tsp garlic powder: adds a gentle savory note.
• 1/4 tsp onion powder
• 1/4 tsp dry mustard: sharpens the cheddar flavor.
• 8 oz sharp cheddar cheese, shredded from a block: pre-shredded won’t melt as silky.
• 1/2 cup sour cream: for tang and extra creaminess.
• For the topping:
• 2 cups crushed cornflakes: measure after crushing.
• 3 tbsp unsalted butter, melted: tosses with the flakes.

Variations and Substitutions

• Cheese swap: Replace cheddar with Gruyère or a smoked gouda for a different depth.
• Add a little heat: Stir in a minced chipotle pepper or a pinch of cayenne to the sauce.
• Gluten-free option: Use cornstarch instead of flour (1 1/2 tbsp) and gluten-free crushed crackers for the topping.
• Extra protein: Fold in 1 cup diced ham or cooked bacon before baking to turn it into a main dish.

If you like this, try my Scalloped Potatoes.

How to Make Creamy Cheesy Potato Casserole

Step 1: Make the Cheese Sauce

Preheat your oven to 350°F (175°C) and grease a 9×13 baking dish. In a medium saucepan over medium heat, melt the 3 tablespoons of butter. Whisk in the 3 tablespoons of flour and let it bubble for about 1 minute, just until it smells nutty. Slowly pour in the 2 cups of milk while whisking constantly to avoid lumps. Add the 1 teaspoon salt, 1/2 teaspoon pepper, 1/2 teaspoon garlic powder, 1/4 teaspoon onion powder, and 1/4 teaspoon dry mustard. Keep whisking and bring to a gentle simmer; cook for about 5 minutes, or until the sauce coats the back of a spoon.

The sauce will look thin initially but thickens noticeably after a few minutes of simmering; don’t rush it. Once thickened, remove the pan from the heat and stir in the 8 ounces of shredded cheddar and 1/2 cup sour cream until smooth and fully incorporated. A quick taste here lets you adjust salt before it goes in the oven.

Step 2: Mix the Potatoes

Place the diced potatoes in a large bowl. Pour the cheese sauce over them and use a spatula to fold everything together until every piece is well coated. Scrape the mixture into the greased baking dish and spread it into an even layer.

The sauce might seem a little loose, but it will set up as the potatoes bake. Make sure no dry potato pieces are hiding at the bottom; a thorough stir ensures even cooking.

Step 3: Top the Casserole

In a small bowl, combine the 2 cups of crushed cornflakes with the 3 tablespoons of melted butter. Toss with a fork until the flakes are well coated. Sprinkle this mixture evenly over the potatoes, covering the surface completely.

A solid, even layer of topping is what gives you that crispy top in every bite. If you have a few bare spots, the cheese sauce will bubble up and form a chewy crust instead, which isn’t a bad thing, but the cornflakes are the highlight.

Step 4: Bake the Casserole

Slide the dish into the preheated oven on the middle rack. Bake for 30 to 35 minutes, until the topping is deep golden and the sauce is bubbling vigorously around the edges.

After about 30 minutes, peek through the oven window; the top should be a uniform golden brown. If it’s browning too fast, tent loosely with foil for the last 10 minutes.

Step 5: Scoop and Serve

Remove the casserole from the oven and let it rest for 10 minutes on a cooling rack. This pause helps the sauce firm up so your first scoop holds its shape. Use a large spoon to dish generous portions onto plates, showing off those creamy layers.

Serve while it’s still piping hot, the cheese stretchy and the cornflakes crisp. The resting time is just enough to keep you from burning your tongue but not so long that the casserole cools down.

Tips for the Best Cheesy Potato Casserole

• Dice the potatoes uniformly, about 1/2-inch cubes, so they cook through at the same rate. Irregular pieces risk some being undercooked while others turn to mush.
• Don’t skip the resting period after baking; that 10 minutes lets the sauce set up and prevents a soupy first serving.
• If your cheddar is particularly sharp or salty, reduce the added salt by a quarter teaspoon and taste the sauce before mixing.
• For a make-ahead option, assemble the casserole without the topping, cover, and refrigerate overnight. Add the cornflake topping just before baking and tack on 5 to 7 extra minutes in the oven.

Bake times can vary a little depending on your baking dish:

Storing and Reheating Leftovers

• Refrigerator: Store leftovers in an airtight container in the fridge for up to 4 days. The topping will soften, but it still tastes great.
• Reheating: Warm individual portions in the microwave, or cover the casserole dish with foil and reheat in a 300°F oven for about 15 minutes. The oven will help re-crisp the top a little.

What Goes Well With Cheesy Potato Casserole

This casserole pairs with anything that benefits from a creamy, cheesy side. It’s a natural with roasted chicken because the crispy skin contrasts the soft potatoes. For a holiday plate, serve it next to a glazed ham; the sweet and salty combo works every time. It’s also great with a simple meatloaf, soaking up the tangy glaze.

Frequently Asked Questions

Can I add bacon or ham to this casserole?

Yes. Stir in up to 1 cup of cooked, chopped bacon or diced ham when you mix the potatoes with the sauce. This turns the side into a hearty main dish; just increase the bake time by 5 minutes to account for the cold additions.

Why did my topping turn out soggy?

Sogginess usually happens from not draining the potatoes or from covering the casserole while it bakes. Make sure your potatoes are thoroughly dry after rinsing, and bake uncovered the entire time so moisture can escape.

Can I freeze the casserole?

Absolutely. Assemble the casserole without the cornflake topping, let it cool completely, then wrap tightly and freeze for up to 2 months. Thaw overnight in the refrigerator, add the topping, and bake as directed, adding 10 to 15 minutes until heated through.

Cheesy Potato Casserole Recipe

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Prep Time 20 minutes mins

Cook Time 35 minutes mins

Total Time 55 minutes mins

Servings: 8 servings

Calories: 420

Ingredients Method Notes

Ingredients

  

• 3 lbs russet potatoes, peeled and diced into 1/2-inch cubes
• 3 tbsp unsalted butter
• 3 tbsp all-purpose flour
• 2 cups whole milk
• 1 tsp kosher salt
• 1/2 tsp black pepper
• 1/2 tsp garlic powder
• 1/4 tsp onion powder
• 1/4 tsp dry mustard
• 8 oz sharp cheddar cheese, shredded
• 1/2 cup sour cream
• 2 cups crushed cornflakes
• 3 tbsp unsalted butter, melted

Method

 

1. Preheat oven to 350°F (175°C) and grease a 9×13 baking dish. In a saucepan, melt 3 tbsp butter over medium heat. Whisk in flour and cook 1 minute. Slowly whisk in milk, then add salt, pepper, garlic powder, onion powder, and dry mustard. Bring to a simmer, whisking until thickened, about 5 minutes. Remove from heat and stir in cheddar and sour cream until smooth.
2. Place diced potatoes in a large bowl. Pour the cheese sauce over them and fold until evenly coated. Transfer to the prepared dish in an even layer.
3. Mix crushed cornflakes with 3 tbsp melted butter and sprinkle evenly over the potatoes.
4. Bake for 30-35 minutes, until topping is golden and sauce is bubbling.
5. Let rest for 10 minutes, then scoop servings onto plates.

Notes

The rest time after baking is important, it allows the sauce to thicken so the casserole slices neatly. If your cornflakes start browning too fast, tent the dish loosely with foil for the remaining bake time.