Au Gratin Potatoes
Updated
Updated
With thinly sliced potatoes, onions, and two kinds of cheese, this is my go-to recipe for simple Au Gratin Potatoes—they’re the perfect side for holiday ham or turkey, and just as good with weeknight pork chops or steak. I also love that they can be prepared ahead of time, which makes dinner so much easier.
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This has become my go-to side dish for any potluck gathering or my own dinners where I entertain guests. It’s perfectly fine using just cheddar cheese if you don’t have Gruyère; however, the Gruyère makes it extraordinary. A terrific dish that can be made the day before. So easy; so good!
– Virginia
This au gratin potatoes recipe is one of those side dishes that sounds a bit fancy, like something you’d order at a restaurant, but is quite simple to make. All you need is potatoes, onions, cheese, and a few pantry staples. These are another example of how sometimes the most basic ingredients can result in such an impressive dish.
Though very similar, au gratin potatoes and scalloped potatoes are terms that are often used interchangeably; both dishes are made with sliced potatoes and onions, though au gratin potatoes are sometimes considered “fancier” and are typically topped with breadcrumbs or cheese, while scalloped potatoes usually have a cream sauce.
I love to serve these au gratin potatoes as a holiday side dish, but they are simple enough to make for a regular weeknight dinner, too. Sometimes, I’ll make them even more hearty by adding diced cooked ham or bacon crumbles. And bonus, they can be assembled in advance, which is perfect for those busy evenings.
Helpful Tips
- Slice potatoes no thicker than ⅛ inch. Any thicker and they won’t fully soften in the center, even if the top looks golden. Uniform slices ensure even cooking. I like to use a mandoline.
- Shred your cheese fresh from the block. Pre-shredded cheese contains anti-caking agents that prevent smooth melting and can make the sauce slightly grainy.
- Cover the dish tightly with foil for the first bake. This traps steam and allows the potatoes to cook through before the top browns. If it’s loosely covered, the edges cook, but the center stays firm.
- Don’t skip the 15-minute rest. The sauce continues to thicken as it cools slightly, making the casserole easier to slice and preventing a runny texture.
- Use russet potatoes for the best structure. Their higher starch content helps thicken the sauce and keeps the layers intact. Yukon Golds taste great, but can turn slightly softer and less defined.
- If the sauce turns watery, the roux likely wasn’t cooked long enough. Make sure there are no white streaks of flour, and it smells lightly nutty before adding the milk.
- If the sauce curdles or looks grainy, the heat was too high. Keep the cheese sauce at a gentle simmer and avoid boiling after the cheese is added.
- Always test doneness with a knife in the center. It should slide in easily with no resistance. If there’s any firmness, bake a little longer, even if the top is already browned.
Au Gratin Potatoes
Ingredients
- 6 medium russet potatoes, peeled
- 1 small sweet onion, sliced thin
- ¼ cup butter
- ¼ cup all-purpose flour
- 1½ cups whole milk
- 2 cups freshly shredded cheddar cheese
- 1 tsp garlic powder
- 1 tsp salt
- 1 tsp pepper
- ½ cup shredded Gruyère cheese, (or use more cheddar)
- fresh chopped chives or parsley, for garnish
Instructions
- Preheat your oven to 375°F. Spray a 2-quart casserole pan with nonstick spray.
- Thinly slice the potatoes to no more than ⅛ inch thick. I highly recommend slicing the potatoes using a mandoline.
- Arrange half the potatoes in the casserole pan and top with the onions. Top the onions with the remaining potatoes.
- In a medium saucepan, melt the butter. Slowly stir in the flour and cook for 2 minutes until no white streaks remain, stirring the entire time. Slowly whisk in the milk until well combined. Mix in the cheddar cheese, garlic powder, salt, and pepper until the cheese has melted.
- Pour the cheese sauce over the potatoes.
- Cover the pan tightly with aluminum foil and bake for 45 minutes.
- Uncover the casserole dish and sprinkle the Gruyere cheese over the top. Bake for an additional 35-45 minutes until it is golden brown and bubbling.
- Let rest 15 minutes so the sauce thickens and it's easier to cut, garnish with fresh chopped parsley or chives, then slice and serve.
Video
Nutrition
Nutritional information given is an automatic calculation and can vary based on the exact products you use and any changes you make to the recipe. If these numbers are very important to you, I would recommend calculating them yourself.
Did you make this? Leave a rating below!How to Make Au Gratin Potatoes Step by Step
Gather the ingredients: Gather all the ingredients together. Preheat your oven to 375°F and lightly spray a 2-quart casserole dish with nonstick spray.
Slice the potatoes and onions: Peel 6 medium russet potatoes and thinly slice to no more than ⅛-inch thick. The slices should be uniform so they cook evenly. Slice 1 small sweet onion very thin so it softens fully while baking.
Layer the potatoes: Arrange half of the sliced potatoes in an even layer in the prepared dish. Scatter the thinly sliced onion over the top, then finish with the remaining potatoes, keeping the top layer fairly level.
Make the roux: In a medium saucepan over medium heat, melt ¼ cup butter until fully melted and gently bubbling. Sprinkle in ¼ cup all-purpose flour, stirring constantly for about 2 minutes until no white streaks remain and the mixture smells slightly nutty. The roux should look smooth and pale golden, not browned.
Slowly whisk in 1½ cups whole milk, adding it gradually while whisking continuously to prevent lumps. Continue cooking until the sauce thickens to a smooth, gravy-like consistency that coats the back of a spoon. Reduce the heat to low and stir in 2 cups freshly shredded cheddar cheese, 1 tsp garlic powder, 1 tsp salt, and 1 tsp black pepper. Stir until the cheese is completely melted and the sauce is smooth and velvety. Avoid boiling once the cheese is added to prevent graininess.
Assemble the casserole: Pour the hot cheese sauce evenly over the layered potatoes, gently tapping the dish on the counter to help the sauce settle between the slices.
Bake the casserole: Cover the dish tightly with aluminum foil and bake for 45 minutes. Remove the foil and sprinkle ½ cup shredded Gruyère cheese evenly over the top. Return the dish to the oven and bake for an additional 35–45 minutes, until the top is golden brown and the edges are bubbling. A knife inserted into the center should slide in easily with no resistance.
Rest and serve: Let the casserole rest for 15 minutes before slicing. The sauce will thicken as it cools slightly, making it easier to cut clean portions. Garnish with freshly chopped parsley or chives, then slice and serve.
Serving Suggestions
These au gratin potatoes are one of those cozy side dishes I make when I want dinner to feel a little extra special. They’re perfect for holiday tables like Thanksgiving, Christmas dinner, or Easter brunch, but I also love them for a relaxed Sunday roast or even a casual dinner party. They pair beautifully with roast chicken, prime rib, or glazed ham. I’ll often round out the plate with balsamic bacon Brussels sprouts, roasted vegetables, or a simple green salad to balance the richness. It’s a classic side that works just as well for celebrations as it does for everyday comfort meals.
How to Store
- Prep ahead. To prepare in advance, I like to assemble the potatoes and then store them in the refrigerator until I want to cook them. Let the dish warm up on the counter for 15-20 minutes before you try to throw it in the oven.
- Fridge. Any leftover au gratin potatoes should be stored in an airtight container in the refrigerator for up to 4 days. I don’t recommend freezing this dish.
- Reheat. You can reheat the pan, covered, in the oven or individual servings in the microwave.
More Cozy Comfort Food Sides
- Boursin Mashed Potatoes: Boursin mashed potatoes are ultra-creamy and packed with herby, garlicky flavor thanks to rich Boursin cheese blended right into fluffy potatoes. They’re an easy way to elevate classic mashed potatoes for holidays, dinner parties, or anytime you want a simple side dish that tastes a little extra special.
- French Onion Mac and Cheese: French Onion Mac and Cheese combines sweet caramelized onions with a rich Gruyère and cheddar cheese sauce for a deeply savory twist on classic baked mac and cheese. It’s cozy, indulgent, and perfect for elevating weeknight dinners or holiday sides.
- Cabbage Casserole: This hearty cabbage casserole layers tender cabbage with savory sausage, onions, and a creamy, cheesy sauce for an easy one-dish meal that’s comforting and satisfying. It’s a great way to make cabbage feel cozy and flavorful alongside your favorite mains.
I hope you love this easy delicious recipe – be sure to give it a review below! Also don’t forget to follow Belly Full on TikTok, Instagram, Facebook, Pinterest, and YouTube!
Made these for dinner with friends and for Thanksgiving. Both times they were excellent and everyone loved them. Worth the time & effort!
I made these over the weekend, I didn’t have any Gruyere cheese, but it was still very good.
Next time I want to try them with the Gruyere cheese.
It was delicious.
Took it to a church supper,
Dear Amy,
Can I omit the onions from this recipe and still use all the same amounts of everything else? And also can the whole milk be substituted with heavy whipping cream?
Thanks
Yes, you can omit the onions. Heavy cream might make the sauce very thick and difficult to pour. Half-n-half would be ok.
This has become my go-to side dish for any potluck gathering or my own dinners where I entertain guests. It’s perfectly fine using just cheddar cheese if you don’t have Gruyère; however, the Gruyère makes it extraordinary. A terrific dish that can be made the day before. So easy; so good!
Aloha Amy! This was a big hit at my Thanksgiving luncheon yesterday! Thank you so much for sharing it with us all👏🏽👏🏽👏🏽 I haven’t yet checked your other recipes. But I will surely be doing that today🥰
Mahalo (Thank you)!
Dwyna Potter
Hawaii
Yes, I made them about three weeks ago. Everyone raved about the consistency and flavors. I plan to serve them again tomorrow for lunch. Thanks!
This is so good. We added bacon to ours and it was like baked potato.
Had this tonight and it was a big hit all around! Thank you, I’ll be making it again soon!
My son in law made this for Easter and they are delicious!!
Best au gratin potatoes I’ve ever made! I see heavy cream instead of milk
Can I use gluten free flour?
I’ve never tested this recipe using gluten free flour, so I can’t vouch for results, but you could try it.
My son in law made this for Easter and they are delicious!! He used GF flour too
This was such a delicious addition too our Thanksgiving meal, thanks for sharing!