Potatoes Au Gratin sounds fancy, but it’s easy to make and a delicious way to prepare potatoes!
In this gratin recipe, potatoes and onions are thinly sliced and baked in a rich cheesy sauce until bubbly and golden brown.
They’re perfect for Sunday supper or to serve with any holiday meal!
Scalloped potatoes vs. Potatoes au Gratin
The difference is the cheese.
Technically, gratin is defined as “covered with breadcrumbs or cheese”, and scalloped refers to “baked with milk or a sauce”. However, many people still refer to gratin potatoes as scalloped potatoes.
This Potatoes au Gratin recipe is similar to scalloped potatoes but with a cheesy sauce instead of a white sauce. Either are great with Sunday supper or next to baked ham or meatloaf.
Ingredients for Potatoes au Gratin
- Potatoes: The best potatoes for potatoes au gratin are waxy potatoes like red-skinned or Yukon gold. They hold their shape well, and because they’re thin-skinned, they do not require peeling (extra bonus!).
- Note: While russet potatoes or baking potatoes will work and taste good in this recipe, they’re more starchy and may fall apart once cooked—they’re more suited to mashed potatoes.
- Onion: Thinly sliced onion adds flavor to these potatoes. For a milder flavor, cook the onion in butter first or replace it with 1 teaspoon of onion powder in the sauce.
- Cheese: I use cheese with a lot of bold flavors in this recipe, including cheddar, parmesan, and Gruyere.
- Option: Gruyère cheese adds a rich flavor to the cheese sauce but can be replaced with provolone or Swiss for a similar flavor!
- Sauce: Butter and flour create a roux to thicken this sauce, and I use milk as the base. It’s plenty rich enough with all of the cheese.
How to make Potatoes Au Gratin
Here is a quick overview of the steps for potatoes au gratin.
- Prep: Thinly slice the potatoes and onions.
- Sauce: Make the cheese sauce in a saucepan on the stove.
- Assemble: Stack the potato slices and onions in little piles and then stand them on their sides in the casserole dish.
- Bake: Bake until the potatoes are tender and the sauce is bubbly.
Find the full detailed recipe below.
Holly’s Pro Tips
- For easy prep and even thin slices, use an inexpensive mandoline. You can find them for under $20, and it saves a lot of time.
- Pre-shredded cheese will work in this recipe, however the sauce will be smoother if you shred cheese from a block.
- If swapping the cheese, make sure you use those with bold flavors.
- If you’re short on time, set the potatoes and onions in the dish as directed and cover with plastic wrap. Microwave on full power for about 10 minutes (it will be hot when removing the plastic wrap). Add the cheese sauce and bake as directed below for about 45-55 minutes. Just as delicious… but a little bit quicker!
How to Make Potatoes au Gratin Ahead of Time
This dish can be made 24 hours in advance. Ensure the potatoes are completely covered in the sauce—any exposed bits of potatoes will discolor slightly. Cover tightly with plastic wrap and refrigerate.
Remove from the fridge at least 30 minutes before baking. You may need to add 10 to 20 minutes to the baking time.
While we often eat these as a side, I sometimes make Potatoes au Gratin with ham by including slices or diced leftover ham (from our favorite crock pot ham) before baking.
Did you make this Potatoes au Gratin recipe? Leave us a rating and a comment below.
Potatoes Au Gratin
Ingredients
- 2 ½ pounds red potatoes
- 1 onion thinly sliced
- 3 tablespoons butter
- 3 tablespoons all-purpose flour
- 1 teaspoon dry mustard powder
- 2 cups milk
- 1 cup shredded cheddar cheese
- ½ cup shredded gruyere cheese
- ¾ teaspoon salt divided
- ½ teaspoon black pepper divided
Instructions
- Preheat oven to 400°F.
- Wash potatoes and slice into ⅛" thin slices. Slice onion as thin as possible.
- Season the potatoes and onions with ½ teaspoon of salt and ¼ teaspoon of pepper. Toss well to evenly coat. Layer potatoes and onions into little stacks. Place stacks on their side in a greased 2.5qt to 3qt casserole dish.
- Melt butter and flour in a saucepan and cook 2 to 3 minutes. Add mustard powder, ¼ teaspoon salt, ¼ teaspoon pepper and milk. Whisk over medium heat until thick and bubbly. Remove from heat and stir in cheeses until melted.
- Pour the cheese sauce over the potatoes, gently separating them to allow the sauce to seep between the layers. Cover with foil (sprayed with cooking spray) and bake 60 minutes.
- Remove foil and bake an additional 20 to 30 minutes or until lightly browned and potatoes are cooked. Cool 15 minutes before serving.
Video
Notes
Nutrition Information
Nutrition information provided is an estimate and will vary based on cooking methods and brands of ingredients used.
Course Side Dish
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This turned out so good!! Simple yet delicious!! Just make sure you leave enough time for prep & cooking.
This is a huge hit every time I make it!
I used all gruyere cheese rather than the mix and added about 1/2 tsp of dried thyme to the recipe. ABSOLUTELY DELICIOUS!
DELISH!
I also enjoy the versatility of this recipe.
I was able to use it as a base for a soup I made. So satisfying!
Made this recipe tonight and added the suggested ingredients of rosemary and thyme. I must say the dish was amazing! I taught culinary arts for 8 years and this is hands down the best recipe for this dish I have tasted.
Amazing recipe. I would add some garlic powder to give it some more flavor next time.
So so good. I excluded the onions and added a little bit of fresh tarragon and chives at the end. Used Gruyère as the cheese. Absolutely divine!
Thank you so much, Wendy! ❤️
Followed recipe except used russet potatoes. Very good, empty dish so was a success. TY.
Delicious recipe! I made these for Christmas and they turned out fabulous. Thank you.
I cut the recipe in half for just 4 of us and it was perfect and delicious. I will definitely save this and make it again.
can you make these in a slow cooker?
I haven’t tried this recipe in a slow cooker so I can’t say for sure – dairy doesn’t always hold up in the slow cooker. I use this recipe for making slow cooker potatoes.
Is it possible to par bake, or partially bake, the dish the day before, then finish it just before the meal? If so, what combo of cooking times would you recommend? Thank you! Love the edge-up presentation you created.
I haven’t tried par baking but I do think it would work well with this dish. My estimate would be to bake them for the 60 minutes and then about 30 to 40 minutes the next day. As I haven’t tried it you might allow for extra time just in case, they will stay hot for quite a while. Let us know how it goes!
Tommy, did you try par baking? If so did it turn out okay? I’m hoping you say yes because this would make my day tomorrow much less busy. Thanks!
Excellent recipe, very delicious, but needs at least 25% more sauce.
Adding: I forgot that the potatoes weren’t quite tender at the end of the cooking time, so they got an extra 15 minutes in the oven. And I did make this the day before serving, it worked out very well.
Could this be done in a roaster oven or crockpot?
I have never tried but you should be able to make them in a crockpot. I would follow the cooking instructions on this crockpot scalloped potatoes recipe and cook these the same way. Enjoy!
Thank you for your response. Could i also cook for longer at a lower temperature? We have our meat cooking at 325.
This would be fine cooked longer at a lower temperature but I can’t say for sure how long. I would allow for extra time as they’ll stay hot for quite a while if they’re done early.
I am planning to make these for Christmas! They sound so good!! Can these be put together the night before and baked the next day?
Hi Julie, yes it can be made ahead! Prepare as directed and cool. Once cool, cover with plastic wrap and refrigerate. I would suggest removing from the fridge at least 30 minutes before baking. It may need a little bit extra cook time. Enjoy!
Hi! Im excited to try this recipe!! I was wondering, can I use almond milk for this recipe?
Thank you!
Hi Claire, yes you can use almond milk in this recipe. We would love to hear how it turns out for you!
Can I make this gluten free? If so, would you sub 1:1 flour or use almond flour?
Hi Emily, I have never tried making this dish GF but other readers have used gluten free flour or cornstarch instead with good results. Let us know how it turns out for you!
I plan to make these for Easter. Regarding your gluten free comment that cornstarch or almond flour can be used instead of flour, would one be better than the other? And what amount if cornstarch? Thank you!
To Tanja, A gluten free 1:1 flour would be your best option. And you can replace it with the same quantities as listed for flour in the recipe.
Question… I don’t need to peel the potatoes first? Can I use russets? I can’t wait to try this in a few days!
No need to peel thin skinned potatoes, I would peel russets. You can use russets but they tend to fall apart. You can also find this information in the post:
Just like when making scalloped potatoes, the best potatoes for gratin are red-skinned or Yukon gold potatoes. These two waxy potatoes can hold their shape well and because they’re thin-skinned, they do not require peeling (extra bonus!). While russet potatoes or baking potatoes taste good, they’re more starchy. They do not hold their shape as well and the dish can become mushy, they’re more suited to mashed potatoes.
I have avoided au gratin recipes due to the amount of work they require. This recipe is well worth it! I added some garlic powder and thyme along with salt and pepper and they were fantastic. I will definitely make them again!
Cannot wait to try this recipe for Christmas but a concern of mine is that it will not be seasoned enough for everybody.
Have you ever added cream of mushroom or celery soup to the sauce mix ( condensed, right out of the can) ?
I will definitely add garlic but we do not like Thyme.
Hi Roy, I have never tried adding condensed soup so I can’t say for sure. Please let us know how it turns out if you decide to try it!