These cheesy scalloped potatoes are an easy, oven-baked casserole-style side dish that feeds six and comes together with simple ingredients. Thinly sliced potatoes are layered with sweet caramelized onions and a creamy cheese sauce, then baked until bubbly and finished with a golden cheese and breadcrumb topping. It’s a straightforward, make-ahead-friendly casserole recipe that takes a little prep but very little skill, making it perfect for holidays, Sunday dinners, or anytime you want a comforting potato side that feels special without being fussy.

If you’re looking for potatoes dauphinoise or potatoes au gratin, you’re still in the right place. These dishes are all variations on the same scalloped potato casserole idea, thinly sliced potatoes cooked in a creamy sauce until tender. The names are used interchangeably in modern cooking, and most recipes now blur the traditional lines. This version leans cheesy and creamy, sitting comfortably between classic dauphinoise and au gratin, which is why it works no matter what you searched for.

Table of Contents

Why This Recipe Works:

Its cheesy – Adding a mix of parmesan and sharp cheddar adds a serious upgrade taking this recipe from standard side to comfort food heaven. Its not just potatoes in sauce, its potatoes drenched in flavor.
A roux done right – This roux is well thought out, extra flour to make it thick, a carefully selected blend of seasonings to make this sauce deeply savoury and yet still creamy.
Customisable – This cheesy scalloped potato recipe is still simple enough to be customised or used for any occasion at any time of the year.
Its an easy recipe – The idea of creating a roux might scare off some beginners, but this recipe really is fool proof, even the most inexperienced cooks cant mess up this recipe.

How to make scalloped potatoes:

Step 1: Caramelize the onions

Start by caramelizing the onions. Thinly slice the onions and add them to a wide skillet over medium heat with a little butter or oil. Sprinkle over the brown sugar and cook slowly, stirring often, until the onions are soft, deeply golden, and sweet. This takes around 15 to 20 minutes. Once done, spread them evenly over the bottom of a greased casserole dish.

caramelise onions for the cheesy scalloped potatoes

Step 2: Make the roux

To make the cheese sauce, melt the butter in a saucepan over medium heat. Whisk in the flour and cook for about one minute to remove the raw flour taste. Slowly pour in the milk while whisking continuously, then let the sauce simmer gently until thickened.

Step 3: Build the cheese sauce

Add the salt, pepper, mustard, onion powder, garlic powder, and thyme. Stir well, then add the Parmesan and sharp cheese, stirring until melted and smooth. Remove the pan from the heat and stir in the heavy cream to finish the sauce and keep it silky.

create the roux with butter, flour, and milk

Step 4: Scallop the potatoes

Thinly slice the potatoes to about 1/8 inch thick. Try to keep them even so they cook at the same rate.

Step 5: Assemble the casserole

Layer the potatoes over the caramelized onions, slightly overlapping them. Spoon cheese sauce over the potatoes and spread it gently to coat. Repeat the layers until all the potatoes and sauce are used, finishing with sauce on top.

assemble layers of scalloped potatoes and creamy sauce

Step 6: Add the topping and bake

Sprinkle generously with extra cheese and breadcrumbs. Bake uncovered at 375°F for 30 to 35 minutes, until the top is deeply golden and the potatoes are tender when pierced with a knife.

his almost always comes down to potato thickness. If the slices are too thick or uneven, they’ll take longer to soften. Aim for evenly sliced potatoes around 1/8 inch thick so they cook through in the time given.

Scalloped Potato FAQ

Can I assemble this recipe ahead of time and bake it later?
Yes, this cheesy scalloped potato casserole can be assembled in advance and refrigerated for up to 24 hours. Bake uncovered just before serving, adding a few extra minutes if it’s going straight from the fridge to the oven.

What’s the best way to slice potatoes for scalloped potatoes?
A mandoline gives the most consistent slices, but a sharp knife works just as well. Even thickness matters more than speed or technique.

Why did my cheese sauce split or look greasy?
This usually happens if the sauce gets too hot after the cheese is added. Keep the heat moderate, melt the cheese gently, and always stir in the heavy cream off the heat to keep the sauce smooth.

Can I use pre-shredded cheese?
Yes. Pre-shredded cheese works just fine in this recipe and keeps things convenient. The sauce is thick and forgiving, so you’ll still get a creamy result.

Do I need to cover scalloped potatoes while baking?
No. This recipe is baked uncovered so the cheese and breadcrumb topping can brown properly while the potatoes cook through underneath.

Can I double this recipe?
Yes, just use a larger or deeper casserole dish and allow extra baking time. Check doneness by testing the center with a knife.

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