Potatoes Au Gratin

4.98 from 142 votes
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Delicious au gratin potatoes recipe that’s easy to make during the holidays. It’s the perfect cheesy potato side dish that complements any meal.

Spoon lifting potatoes au gratin from a casserole dish.

Cheesy potatoes au gratin is a classic side dish that’s easy to prepare and is always a crowd-pleaser. Except if the cream curdles or the potatoes aren’t fork-tender after baking, but with the right guidance, I’m going to show you how these common problems can be easily avoided.

This recipe uses multiple layers of thinly sliced Yukon gold potatoes topped with a roux-based sauce to stabilize the milk in the dish. Aged sharp cheddar and buttery gruyere cheese mix together in the sauce and get sprinkled on the potatoes. It’s a comforting dish that can be prepared ahead of time and enjoyed later.

How to make au gratin sauce

The basic technique used to create a milk sauce is using a thickening agent, like a roux. This recipe uses equal parts by volume of butter and flour, which cooks into a paste, then gradually incorporating milk while simmering until the thickness can nicely coat a spoon. You can use heavy cream for an even richer consistency, but the roux makes the sauce velvety enough.

The result is a bechamel with cheese whisked in. This technique is also used in macaroni and cheese, but we’re using potatoes instead of pasta. If made correctly, the sauce should spread easily between the potato layers instead of pooling at the bottom of the baking dish.

How to prevent the sauce from curdling

If you only add milk to the potatoes, the proteins are at risk of curdling over time. Once the protein hits a temperature of 180ºF (82ºC) and above, they begin clumping together. That’s why recipes often use milk and cream because the increased fat helps reduce curdling since there’s less protein.

Considering the potatoes are cooked at 400ºF (204ºC) for nearly an hour to tenderize, it’s best to build a little safety cushion with a roux. The creamy texture added to the sauce is just a tasty bonus!

Cheese selection

two types of cheeses being whisked into a roux-based pan sauce
Step 3. Add the cheeses

The best cheese combination for the au gratin potatoes is gruyere and sharp cheddar cheese. Gruyere is a medium-hard cheese with a nutty taste and a hint of sweetness. It has excellent melting properties, and I always use it when making French onion soup.

Sharp cheddar has a stronger aged flavor and a semi-hard texture. Together they melt effortlessly in the bechamel sauce and create a nice gooey, browned crust on top of the potatoes.

The best potatoes to use for au gratin

Choose a medium-sized waxy type of potato like Yukon gold or gold for au gratin. Once cooked, the flesh has a nice buttery texture, but it holds its shape well when scooping out each serving.

Russets are my second choice because their delicate texture tends to absorb the sauce and become too creamy. I prefer to use Russet potatoes for mashed potatoes instead.

Assemble and bake

In a greased 8-inch square baking dish, layer half over the potatoes, overlapping them. Spread half of the cheese sauce and shredded cheese. Repeat the layering once more time with the remaining ingredients. Cover the dish with foil and bake in a preheated oven at 400ºF (200ºC). This traps the heat to steam and softens the spuds. After 30 minutes, remove the foil so that the cheese layer browns. Cook until the potatoes are tender, about 20 to 25 minutes.

Make ahead

This side dish can be assembled two days ahead, covered, and refrigerated until ready to bake. Bake time may need to be slightly increased as the pan and ingredients will be cold. My family also enjoyed leftovers. It still tastes delicious when reheated.

What’s the difference between scalloped potatoes and au gratin potatoes?

Scalloped potatoes are traditionally cut into thicker rounds, about ¼-inch, layered, and baked in a casserole dish. Cream, milk (or both), and aromatics like garlic, onions, and herbs are added. On the other hand, Au gratin has thinly sliced potatoes, ⅛-inch thick potato slices, and cheese added to the recipe.

You might also sometimes see breadcrumbs sprinkled on top for extra crunch. The culinary terms are often used interchangeably, which causes a bit of confusion.

Serve this with

Potatoes au gratin hot and fresh from the oven.

Starches help to stabilize the cream sauce

The natural starches in flour helps to stabilize the milk emulsion in the sauce, preventing the separation of the oils and fat. When the starches are heated, they can hold onto some of the water in the milk, swell, and create a viscous mixture. A roux in a dairy-based sauce will thicken and stay creamy once baked in the oven.

Potatoes Au Gratin

Potatoes au gratin is a casserole recipe with layers of thinly sliced Yukon gold spuds and a cream sauce that includes melted cheese.
4.98 from 142 votes
Prep Time20 minutes
Cook Time1 hour
Total Time1 hour 20 minutes
Servings 8 servings
Course Side
Cuisine French

Ingredients 
 

  • ¼ cup unsalted butter
  • 1 tablespoon minced garlic
  • ½ cup finely chopped yellow onion
  • ¼ cup all-purpose flour
  • 2 cups whole milk
  • ¾ teaspoon kosher salt
  • ½ teaspoon black pepper
  • teaspoon nutmeg
  • 2 pounds yukon gold potatoes, peeled and cut into ⅛" thick slices
  • 1 cup shredded gruyere cheese
  • 1 cup shredded sharp cheddar cheese
  • 2 teaspoon chopped chives

Instructions 

  • Preheat the Oven – Set the oven rack to the middle position. Heat to 400ºF (200ºC).
  • Make the Cream – Melt butter in a large skillet over medium-low heat. Add garlic and onions, and saute until fragrant, 2 minutes. Add flour, whisk to combine, stir and cook for 2 minutes.
    Gradually whisk in milk and cook until thickened over medium heat, 2 to 3 minutes. Turn off the heat and whisk in salt, pepper, and nutmeg.
  • Add the Cheeses – Add ½ cup gruyere and ½ cup sharp cheddar cheese, and stir to combine.
  • Assemble the Casserole – Grease the bottom and sides of an 8-inch square casserole dish. Layer half of the potatoes in overlapping rows in the dish. Spread half of the cheese sauce over the potatoes. Sprinkle ¼ cup gruyere and ¼ cup cheddar over the sauce.
    Layer the remaining potatoes, followed by cheese sauce, and sprinkle with the remaining gruyere and cheddar cheese.
  • Bake – Cover with foil and place on a baking sheet. Bake for 30 minutes. Remove the foil and continue baking until the potatoes are tender and the cheese is browned and bubbly, 20 to 25 minutes.
  • To Serve – Transfer the casserole to cool on a wire rack for 10 to 15 minutes before serving. Garnish potatoes with chives.

Notes

  • Make Ahead: Assemble, cover, and refrigerate for 2 days before baking. More baking time may be needed as the ingredients and pan will be cold. 
  • Storing: Store in an airtight container in the refrigerator for up to 5 days. Freeze for up to 1 month. 
  • Reheating: Cover and reheat a small portion in the microwave on a high setting in 15 to 30-second increments until hot. Alternatively, cover and reheat in the oven at 350ºF (177ºC) until hot. 

Nutrition Facts

Serves: 8 servings
Calories 168kcal (8%)Carbohydrates 20g (7%)Protein 5g (10%)Fat 7g (11%)Saturated Fat 4g (20%)Cholesterol 21mg (7%)Sodium 256mg (11%)Potassium 548mg (16%)Fiber 2g (8%)Sugar 3g (3%)Vitamin A 275IU (6%)Vitamin C 13mg (16%)Calcium 105mg (11%)Iron 3.9mg (22%)

Percent Daily Values are based on a 2000-calorie diet. All nutritional information is based on estimated third-party calculations. Each recipe and nutritional value will vary depending on the brands you use, measuring methods, and portion sizes per household.

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Jessica Gavin

I'm a culinary school graduate, cookbook author, and a mom who loves croissants! My passion is creating recipes and sharing the science behind cooking to help you gain confidence in the kitchen.

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Recipe Rating




43 Comments Leave a comment or review

  1. Laura says

    Omg, this is fantastic! I followed the recipe exactly with only a pan shape differentiation (I had round and tall, not square) which resulted in a longer bake time. But the flavor! Wow. Just wow. Thank you for this awesome recipe!

  2. AQ says

    Hi Jessica
    Can I prep and freeze this casserole a few weeks ahead of thanksgiving and thaw it the night before and freeze day of or bake frozen the day of?
    Pl lmk
    Thanks in advance.

    • Jessica Gavin says

      Yes, you can prep, freeze, then defrost the casserole in the refrigerator the night before. You could bake from frozen, but it will take a lot longer to account for defrosting the ingredients in the oven.

  3. Shandi says

    Hi Jessica, is it possible to completely assemble this dish, cover tightly and freeze it. Then bake it frozen the day of? Or should I make it, bake it, then freeze it and re-heat the day of? I’m just trying to do as much ahead of Thanksgiving as possible. Thanks for your help!

    • Jessica Gavin says

      If you are baking the casserole within 2 days, I would cover it tightly then refrigerate it, they bake the day of. Let me know how it goes!

  4. Uris says

    What can I use to sub cheddar cheese? My mom gets migraines with cheddar unfortunately! 🙁 thank you!

  5. Judy Caywood says

    Jessica, I love all the science and share these with our youngest son who is interested in all the food science too. Plus you use two of my favorite cheeses!

  6. Jeannie says

    Hands down, BEST Au Gratin Recipe ever!! I’ve been cooking for 50 years and thought I made the best, but I stand corrected!! YOURS are the best!! Thank you for my new recipe! We’ve dubbed them “Holiday Potatoes “ ❤️

    • Jessica Gavin says

      Wow, that a compliment! Thank you for making the potato recipe, so thrilled to hear that you enjoyed it!

  7. Celeste says

    I doubled this recipe for a gathering of friends last night. It was dynamite and got rave reviews! No leftovers. It tasted like a gourmet side dish served at a Michelin 5-star restaurant. It took me longer than 20 minutes to prepare, however. More like 40 minutes because of slicing so many potatoes and grating cheese. I had never made a roux before so I probably worked more slowly than needed. Anyway, it turned out beautifully and I’ll be making this again for holiday dinners.

  8. Lori says

    I made this recipe yesterday and it was a HUGE hit in my house. Very flavorful and creamy. Thanks very much!

  9. Cerrina Jensen says

    My husband said this was my best au gratin ever. I wanted to up my game and looked at about 7-8 versions before picking this one. Score! ???

  10. Jen says

    In the part before the recipe you say to use milk AND cream so the sauce does curdle but the recipe has no mention of cream. Would you add cream or sub half of the amount of milk for cream?

    • Jessica Gavin says

      Hi Hen- FOr this recipe we use a flour-based roux to help stabilize the milk base. The starches help stabilize the emulsion. I was just comparing why for other recipes they might use a combo of milk and cream if you’re not using flour. You don’t have to add additional cream. Sorry for the confusion!

  11. Susan George says

    I made the Potatoes au Gratin for the ladies at the retirement where I live. They were a huge success. The only thing I have to say is ” where do you get the idea that the prep work takes 20 minutes.? It took me at least a half hour jsy to grate the Gruyere, not to mention the sharp cheddar. Then peal and slice the potatoes, make the cream sauce. I’m so glad I started the “prep” time 3 hrs. before I put it in the oven. I wish all of the recipes I looked at on your page gave a more realistic prep time. I also made the green beans with almond, again delicious and well received, but 10 minutes prep time? Are you kidding me? Just grating the orange rind and squeeze juice took longer then that. I don’t have a modern kitchen, or a ” sous chef”, all my work is done by hand myself with my 73 year old hands and arms. I will keep these recipes and probably make them again as they were so good, I just wish they were written with real people in mind.

  12. Kathy E. says

    This was a fantastic side dish for our Christmas dinner! It went perfectly with our ham and other sides. I used fat-free half and half mixed with skim milk and the sauce was still thick and so rich. It was the only dish that was completely emptied! Thank you for a winner!

  13. Ryan Haley says

    This method is perfect, I’ve been using it for years and it’s so consistent! I’m wondering if you’ve ever assembled it the night before baking? I’m concerned that the potatoes might oxidize and leave me with grey au gratin? ?

    • Jessica Gavin says

      Yukon gold potatoes don’t oxidize are severe as russets. As long as you cover it in the sauce, cheese, and tightly cover in foil in the refrigerator you can assemble it the night before.

  14. JB says

    Has anyone made this recipe the day before and just popped it in the over before dinner? If so how did it turn out..also..if cladding cream do I just substitute for milk or add to the milk?

    • Jessica Gavin says

      Hi There! I think you can assemble everything and then bake with the unmelted cheese before serving, just test to make sure the potatoes are warmed through since it will be refrigerated. What is cladding cream?

      • JB says

        Sorry not cladding …I meant using cream…if I’m using cream so I substitute one for one with milk or add cream in addition to the milk

  15. Alysa says

    Do not make this ahead of time and refrigerate overnight. The potatoes will turn brown. Trust me, I did this and they looked terrible.

    • Jessica Gavin says

      Hi Alysa! What part did you make ahead? Was it the entire recipe, or did you just slice the potatoes? Sliced potatoes will turn brown when exposed to air if not submerged in water, or cooked within a few hours (or less!).

  16. DawneSN says

    The recipe looked excellent, especially because you include nutmeg. I made it yesterday ahead of time, put in in the fridge, about 2 hours before dinner baked it beginning at 350 then moved it up to 400 for the last hour with foil on top until the last half hour. I liked that discoloration was not much of a problem as the sauce covered the potatoes well.

    I changed the recipe a bit because I didn’t have Swiss cheese, sadly, so used a merlot cheddar and a well aged white cheddar. I also doubled the onions and could have doubled them again. I thought the dish was bland. I’d make it again, but I’d add more salt and pepper and more nutmeg (mine was not super fresh).

    Our guest loved it and my husband and I added more salt and pepper.

  17. Carmelite Lofton says

    Hello Jessica
    This was my first time making this dish. I cut the recipe in half because I didn’t need to feed eight. It was perfect and easy and absolutely delicious! I did use smoked Gouda cheese instead of the Gruyere! I am so excited how tasty this dish was and can’t wait to serve it when my family comes for a visit. I look forward to checking out some other recipes!

    Thanks Again

  18. Kim says

    These were a HUGE hit for yesterday’s Easter dinner! My son was so disappointed that there were not enough for leftovers!

  19. Gwyneth Nicholson says

    Can I make this the night before through step 8, then pop it into the oven an hour before Easter dinner?

  20. Whit says

    Well I haven’t made au gratin potatoes since my husband and I got married 9 years ago. Let’s just say it was bad… really bad. Although I could barely make fried chicken let alone au gratin potatoes. I now am far enough I make my own bread and generally cook most everything we eat as fresh as I can. He’s been asking for them lately and I’ve been a little hesitant to say the least. This was a very thorough and easy to follow recipe. I thought it turned out excellent. Thank you. This is one I’ll definitely be writing down.

  21. Judy says

    Hey Jessica,
    I made this recipe last night. My husband kept commenting on how delicious it is and that he was amazed what a good choice both cheeses are in there. : ) Thanks for helping me look like a fabulous cook although I always give you the credit for all these fantastic recipes.
    Judy

  22. Tomiko says

    I can hardly wait… the potato dish is baking for large crowd tomorrow (moch-making crowd), so, I needed this recipe today. Always wondered about previous recipes where curdling occurred. I appreciate the lessons.

  23. Judy says

    Another knockout recipe Jessica. Beautiful, can taste it with my eyes. Definitely sharing with my boys who like to cook. I ordered my youngest your cookbook for Christmas. He is a brainiac and will enjoy the science.
    Thank you
    Judy