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.
This is an outstanding recipe. I have never written a recipe review before, despite looking up and cooking hundreds of recipes. Use the best cheese you can buy. The stand on its side style presentation is delightful. I sprinkled Parmesan on top after removing the foil. Do not leave in the oven or the sauce will separate…still spectacular, but less pretty. I have printed this recipe in 4 sizes for 4,8, 12 and 16 servings
Yummy. I think I thickened the sauce a bit too much and missed out on more crispy edges as they were coated with cheese sauce. Next time I will add some cayenne to give it a little kick too. Despite time it took, will try again!
These are wonderful and I’ve made many potato au gratin recipes. My son-in-law who loved anything potato rates these as the best ever.
I agree. The dish looks so pretty too. Never thought of stacking that way.
Marvelous!
wonderful au gratin potatoes and lots of great tips and tricks… really enjoyed reading it all!!
Planning to make this tomorrow. Could I add fresh cilantro?
I haven’t tried cilantro so I can’t say for sure, but it would change the flavor of this dish. If you try it I would love to hear how it turns out Karlene!
This was so delicious
The most amazing au gratin potatoes I’ve ever had, hands down! Yummy!
Recipe Rating
I am not a cook and frankly do not enjoy cooking. Once a week, I have my daughter and her family over for dinner, usually after a sporting event. Desperate for recipes that are vegetarian, delicious, and easy, I happened upon this version of potatoes au gratin. It was fun stacking the potatoes and onions. The suggestion to arrange the stacks on their sides made presentation very pretty. It was a hit with everyone.
I am so happy to hear you loved this recipe Deborah!
Delicious potatoes. I used a combination of cheeses that I had: about 1/3 Swiss and the remainder was an easy melt type that was mostly Cheddar. The only thing I would change is the stated prep time. Even using a food processor to slice the potatoes (which took less than 5 minutes), it took me much longer to get this in the oven. Another keeper from Holly!
When making half the recipe should I cut down cooking time ?
If halving, the cook time will likely need to be reduced. When your dish is lightly browned and your potatoes are cooked, it will be ready to serve!
If you’re using russets do NOT do these ahead of time. They got gross. They turned black. They tasted fantastic. So we put some more cheddar on top baked them some more. Made mashed as a back up but no one ate them. We said close your eyes and eat. Best I ever had.
These were FANTASTIC!!! Served at Easter dinner and the whole family loved them. I love how they looked with the potatoes standing upright. Thanks for the recipe
I made this for Easter. It tasted really good!! The only change I made was adding a little cream cheese and sour cream to the cheese sauce (because I only had skim milk and wanted a creamier and richer sauce – I believe this defeats the use of skim milk, lol!).
I did follow the overnight instructions; unfortunately some of my potatoes still turned browned, even with plenty of sauce on top. Next time, I’ll try microwaving the potatoes and onions 1st (like instructed above), then put on sauce and refrigerate.
Thx for this recipe; and I’ve enjoyed many other recipes from this website!
can you substitute all purpose flour with Almond flour? will it change the consistency of the sauce?
I haven’t tried it so I can’t say for sure how well the sauce would thicken.
I have used rice flour as a substitute for all purpose flour in homemade cheese sauces with good results.
Wondering if leftovers can be frozen after being baked? Thanks!
I have never tried freezing it so I can’t say for sure. If you try it I would love to hear how it turns out!
Hello! Has anyone omitted the onions and used onion powder instead? If so, how much did you use? I’m not sure if the kiddos at Easter would like the texture of the onions in the casserole. Btw, I’ve previously made this recipe as is, and it’s delish!
I haven’t tried that Lisa but I think it should work just fine! I would use 2-3 teaspoons of onion powder. If you try it I would love to hear how it turns out!
I omitted the onions (because of my daughters food sensitivity’s) and added 1 teaspoon of onion powder and 1 teaspoon garlic powder, it came out delicious!
Made these fo supper tonight. Made 1/2 the recipe as just two of us. They were great. Thanks for the recipe
Well Miss Holly! Thank you so much for this Au Gratin Potato recipe. I had not planned ahead to make this. It was Hubby request to have with the Ham. So I had most of the ingredients, but not enough milk, and being 13 or 17 miles from the nearest store, I had to substitute. Used 1 can of No MSG Cream of Mushroom soup and completed the milk to the 2 cups with Organic Half and Half. (oh how rich and calorie laden. Yummy.) The Ground Mustard, how unique. I have in the past, just threw all the ingredients together in the casserole dish. But, I made the cheese sauce per your instructions and much prefer Your way . I also had a 3rd of an Orange Bell Pepper and a hand full of Parsley that I HAD to use before it went on the edge and have to be fed to the resident Opposum that shows up at night with it’s pointed face self when the temperatures are about 20° (North Cental Minnesota) looking for scraps of food or empties the bird feeders. Used the Sharp Cheddar and Gruyere.
Anyway, The dish is in the oven and smelling Great! It is not Beautiful like yours, I had to just go for function (too big a hurry for the Artistic expression Hahaha! or… too lazy. Ha!).
Looking forward to checking out some of your other Recipes now. You’re a Good cook! Thanks for working so hard to Share!!! Appreciate it.
Sounds wonderful Olivia! I am so glad you enjoyed this recipe!
I followed the instructions to a T I even used the tip to shred my own cheese. I just didn’t like this recipe and neither did my family. :/
It had a strong onion taste and not a lot of any other flavor. Plus it felt like there wasn’t enough sauce. I bought a 5lb bag if potatoes and used half so I had the right measurements.
Ended up making a different recipe a few days later using a combo of this recipe and that one. melting butter and sautéing a few garlic cloves, adding the flour and then adding 1.5 cups of heavy cream and a half cup of whole milk, melting in the 1c sharp cheddar and .5c Gruyère with 1.5 tap salt and a bunch of pepper, a tsp of bouillon and some onion powder and left out the onions. It was amazing.
Sorry I didn’t like the original but stealing some of the instructions and applying them to a different recipe helped make something I loved.
I halved the recipe and it made a delicious, comforting lunch for my husband and me, along with a nice glass of chardonnay. I used Jarlsberg and parmesan, and added some thyme. Wonderful recipe, thank you!