Potatoes au gratin is the perfect side dish for Sunday supper or as a make-ahead holiday side dish. Tender layers of potatoes and onions are baked in a rich, creamy, cheesy sauce until hot, bubbly, and golden.
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Holly’s Recipe Highlights
This recipe makes creamy potatoes, similar to scalloped potatoes but loaded with rich cheesy flavor. They are the perfect dish next to a baked ham, roast beef tenderloin or pork tenderloin.
- Flavor: Creamy, cheesy, and comforting with a golden, slightly crispy top that makes every bite irresistible.
- Why it works: A cooked roux thickens the sauce so it coats the potatoes instead of pooling thin at the bottom.
- Recommended Tools: To save time on prep and make even and thin potato and onion slices, use a mandoline or the side of a box grater.
- Time-Saving Tip: For the holidays, I usually put it together ahead of time and then bake it fresh just before serving. It makes life so much easier.
Scalloped Potatoes vs Potatoes au Gratin
So what is the difference between scalloped potatoes and au gratin potatoes? They’re both very similar, containing potatoes (and often onions) baked in a creamy sauce. Au Gratin is defined as covered with breadcrumbs or cheese, scalloped refers to “bake with milk or a sauce”.
In the case of this recipe, the difference is the cheese. That being said, the term scalloped potatoes is still often used if there is cheese within the dish!
Best Potatoes to Use for Potatoes au Gratin
Red-skinned or Yukon Gold potatoes are best for gratin because they hold their shape and don’t need peeling, while starchy russets can turn mushy and are better for mashing.
- Onions: Slice paper-thin so it softens fully and doesn’t stay crunchy.
- Mustard Powder: A small amount enhances the cheese flavor (I also add it to my baked mac and cheese!). Swap in a little Dijon stirred off the heat.
- Cheese: For the best potatoes au gratin, use bold, sharp cheeses like Gruyère or cheddar, with provolone or Swiss as good substitutes.
- Variations: Add flavor with minced garlic, garlic powder, or fresh herbs like thyme or rosemary. You could also include ham or cooked bacon for a heartier casserole.
How to Make Potatoes Au Gratin
- Prep: Thinly slice the potatoes and onions (full recipe below).
- Assemble: Stack the potato slices and onions in the casserole dish.
- Sauce: Cook the cheese sauce in a saucepan, then pour it over the potato and onion slices.
- Bake: Bake until the potatoes are tender and the sauce is bubbly.
PRO TIP: For a quicker version, layer potatoes and onions, cover, and microwave 10 minutes. Add cheese sauce and bake 45–55 minutes as directed. Just as delicious, but a little quicker!
Make-Ahead, Storing, and Reheating
Make up to 24 hours ahead. Keep potatoes covered in sauce, cover tightly, and refrigerate. Bring to room temperature before baking, and add 10–20 minutes to the bake time.
Leftover potatoes au gratin will keep in the refrigerator for up to 4 days. Let it cool completely, then cover tightly with plastic wrap, or transfer to an airtight container before refrigerating.
To freeze, allow it to cool completely and wrap the dish well with both plastic wrap and aluminum foil, or portion it into freezer-safe containers. It will keep for up to 2 months in the freezer.
For best results, thaw overnight in the refrigerator before reheating. Reheat covered in the oven at 350°F until hot throughout (about 20 to 30 minutes), removing the cover near the end to crisp up the top again. Avoid microwaving frozen potatoes, as it can make the sauce grainy and the potatoes watery.
More Holiday Side Dishes
Did you make this Potatoes au Gratin recipe? Leave us a rating and comment below.
Ingredients
- 2½ pounds red potatoes
- 1 medium 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 thinly 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.
- In a saucepan, melt butter and flour and cook for 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 the stacks to allow the sauce to seep between the layers. Cover with foil (sprayed with cooking spray) and bake for 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
- Slice potatoes as thinly as possible.
- Shred your own cheese from a block for the best results. Fresh herbs (such as thyme or rosemary) and garlic can be added to the sauce if desired.
- To reduce baking time, wrap a microwave-safe casserole dish in plastic wrap before adding the cheese sauce and microwave on full power for about 10 minutes (be careful, it will be hot when removing the plastic wrap). Add the cheese sauce and bake as directed for about 45-55 minutes.
- Additional cheese (cheddar or parmesan) can be sprinkled on top once the foil is removed if desired.
- Store leftovers in an airtight container for up to 4 days. Reheat in the oven or the microwave.
Nutrition Information
Nutrition information provided is an estimate and will vary based on cooking methods and brands of ingredients used.
Course Side Dish
Cuisine American, French© SpendWithPennies.com. Content and photographs are copyright protected. Sharing of this recipe is both encouraged and appreciated. Copying and/or pasting full recipes to any social media is strictly prohibited. Please view my photo use policy here.
mmmm chese
What kind of cheddar is preferred? White cheddar? Orange cheddar? Sharp etc…
Thank you in advance. I like to follow recipes to a T
I like to use a sharp cheddar. Enjoy!
I made these for Thanksgiving and they were a HIT! Added some chopped fresh thyme and rosemary to the cheese sauce, otherwise followed the recipe exactly. The cooking times and helpful instructions were spot-on. Will definitely make again – thanks for the recipe!
Making this for Thanksgiving dinner at boyfriends request. I made it a few months ago and it was delicious.
Hi! Can you do it without the onions?
Hi JP, it will slightly change the flavor but will still be delicious! Enjoy!
this recipe is delicious. I have made it several times.
Made these for dinner tonight and it’s so good! Best potatoes au gratin recipe I’ve tried!
Definitely will be making this again! I used what I had – Sharp cheddar, Colby Jack and russets – and it was delicious! Everything else followed your recipe even using to “10 minute microwave tip”. Thank you for a new family favorite that’s so much better than the box.
What baking time would you recommend if I wanted to turn these into potato stacks in a muffin tin?
I’ve made the original recipe, omitted dry mustard just because I didn’t have any, turned out great.
I have not tried it Lindsay so I can’t say for sure. I would still preheat the oven to 400°F and check them after about 25 minutes. If you try them I would love to hear how they turn out!
Really delicious recipe with clear-cut instructions. A sure-fire crowd pleaser!
We absolutely loved this!! I made with smoked pork chops and my boyfriend said this meal was amazing.
Tried this and not being very good in the kitchen. It turned out wonderful. Easy and Delish. Added a side salad and dinner was done. I did add crumbled bacon bits as my meat serving.
Family loved it!
So glad to hear how much you love these potatoes Debbie! Bacon makes everything better!
This is the best au gratin potatoes ever. Cook and enjoy the taste
I used the gruyere cheese. Fabulous
if all you want to taste is mustard, this recipe is for you. i tried to salvage it by adding more cheese, it didn’t work. such a waste of ingredients. one star for the idea of microwaving the potatoes and onions to soften them to cut down on bake home.
Sorry to hear that, Melissa! Make sure you are only using one teaspoon of dry mustard powder in this recipe. But you can also reduce it if you are finding that the flavor is still too strong for your liking.
Can I take out the dry mustard?
You can leave the dry mustard out and while it will slightly affect the flavor, will still be delicious. If you try it I would love to hear how it turns out!
Did you use dry mustard? You can barely taste it in my sauce
Never had that problem before. Very subtle in my sauce.
Are you sure you only added ONE Teaspoon of DRY mustard? There is no way that anyone could taste mustard at all with that small amount. Not trying to be rude or anything. I’ve misread instructions before and F’ed up a recipe. lol…..
Even though this dish is time consuming, it’s absolutely worth every second you put in. I had family over tonight that I was cooking for the first time and this dish was an absolute hit! I only made very small alterations (most of which were suggested somewhere on the page like adding garlic and thyme). If you’re having people over you want to impress, look no further my friends. Give yourself plenty of time to prep. Slicing the potatoes and onions and then stacking them is more tedious than I expected. Don’t worry, all your hard work will pay off when you see how quickly this dish disappears. I’ll be saving this recipe for the rest of my life haha. It’s creamy, cheesy, and dreamy y’all. Another reviewer said it right… potato HEAVEN
So happy your guests loved this recipe, Sara! To help speed this recipe up we love using a mandoline to prep the potatoes and onions.
Company just cancelled 1.5 hours before arrival due to illness. Potatoes all made but not cooked yet. Can I freeze for another day?
Hi Cathy, that’s too bad! I have never tried freezing this recipe, so if you do please let us know how it turns out. It would probably be best to prebake this recipe or at least partially bake before freezing but let us know how it turns out for you!
Perfect as written! The subtle touch of dry mustard is a plus, as well as everything about the recipe!
I used sharp cheddar and that white cheese
. After baking for an hour I uncovered it to discover a thick layer of oil on top. I still baked for another half hour to try to brown it but didn’t because of the oil. Why did I get so much oil? Also how can I fix that?
Hi Brad, we recommend shredding your own cheese for this recipe to help prevent that. Preshedded cheeses have added preservatives that can cause them to be a bit on the oily side. You could try dabbing the oil with a paper towel to absorb some off the top and then browning it.
These are absolutely the most delicious potatoes I’ve ever eaten…. And I grew up on a potato and dairy farm!! I used extra sharp cheddar, Gruyère and half and half! Probably a little extra cheese…. I cooked as written and they were just amazing… labor intensive, but worth every minute!!! I wish I could use my photos!!
Hi, just a quick question. Can these be mae in the slow cooker? I’d like to make them for Easter but have limited oven space. Thank you for your time.
That should work well. I would follow the cooking instructions on this cheesy scalloped potatoes recipe. Enjoy!