Caramelized Onion Potato Gratin

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Give me all the gratins please!! This Cheesy Potato Gratin is one for the record books and you need it STAT.

Cheesy Potato Gratin from www.whatsgabycooking.com (@Whatsgabycookin)

I mean, what’s not to love about thinly sliced potatoes layered with caramelized onions, heavy cream, tons of cheese, herbs, salt and pepper? It’s basically the most magical side dish on the planet. And I am NOT to be left alone with it.  Somehow this Cheesy Potato Gratin always disappears very quickly and I don’t want to be held accountable.

This will be making an appearance on my holiday dinner party table this year and I am 100% confident in saying you should be doing the same. TRUST. It’s the best. Potato Gratin for EVERYONE.

Cheesy Potato Gratin from www.whatsgabycooking.com (@Whatsgabycookin)
Cheesy Potato Gratin from www.whatsgabycooking.com (@Whatsgabycookin)

Cheesy Potato Gratin

5 from 14 votes
Prep Time 10 mins
Cook Time 1 hr 10 mins
Total Time 1 hr 20 mins
Course Side Dish
Cuisine French
Servings 8 people

Ingredients
  

  • 2 pounds Yukon Gold potatoes (Russet potatoes also work as do sweet potatoes or a combination of any of the above)
  • Kosher salt and freshly ground pepper
  • 1 tablespoons olive oil
  • 1 yellow onion diced
  • 1 1/2 cups heavy cream
  • 1 cup shredded Gruyère cheese
  • 3/4 cup shredded parmesan cheese
  • 1/4 cup crème fraîche or mascarpone cheese
  • Fresh thyme for garnish

Instructions
 

  • Preheat an oven to 400°F. Grease a 9-inch baking dish with butter or non-stick cooking spray.
  • Cut the potatoes into 1/8 inch slices. Arrange the slices, slightly overlapping, on the bottom of the baking dish and season with salt and pepper.
  • In a medium skillet, heat the olive oil over medium high heat. Add the onion and sauté until starting to caramelize, about 8-10 minutes. Add the heavy cream and bring the liquid to a simmer. Simmer until slightly thickened, about 5 minutes. Stir in 3/4 cup of the gruyere cheese and all of the parmesan and cook until smooth and melted. Remove the mixture from the heat, let cool slightly and stir in the crème fraîche. Season with salt and pepper.
  • Pour the cream mixture evenly on top of the potatoes and sprinkle the remaining 1/4 cup of Gruyere cheese evenly on top. Bake until golden brown and bubbly and the potatoes are fork tender when pierced with a knife, about 45 minutes to 1 hour. Let the gratin rest for about 15-30 minutes before serving. Garnish with thyme and serve.

102 Comments

  1. Mmmm. I think these will be a feature on my holiday table as well. I love everything about this – even the pan you have them in!

  2. I cannot wait to make this for a bday dinner on Friday night! I just read the recipe, and am I supposed to layer potatoes then a portion of the melted cheese/cream/onion mixture and repeat? The recipe reads like I’m to layer all of the potatoes and then pour all of the mixture on top, but I’m afraid I’m misunderstanding the steps.

    Thanks!

  3. Hi, so excited to try! To make in advance, would you recommend completely pre-baking, par-baking or assembling then covering and put in fridge for the next day (would the potatoes brown if not at least partially baked?)?

  4. The two times I’ve tried making a gratin, the cream breaks and it’s a watery mess. Does mekting the cheese in the cream help prevent this? Thanks!

    1. have you tried this recipe? Or the cream breaks in other recipes you’ve tried? I’ve never had an issue with this one

  5. Can this be easily doubled or tripled? If so, would you double all ingredients? I do a large party every year (plan for 50 people) and am needing some new ideas this year.

  6. Oops, I meant to say would this dish work in a 9×13 pan? Sorry for the error and thank you for your quick response.

  7. Hi Gaby!

    Would it work to prep this entirely and then wait 2 hours before baking it in the oven? I want to make for Christmas lunch but am not at my house and don’t want to prep it away from home. It would sit with the creme & cheese mixture for a couple of hours.

    1. Awesome! Thank you!
      We just made your 5 cheese penne for my moms birthday dinner and it was the HUGEST hit!! Loooooved it!!!!

  8. Gaby, This is the best potato gratin and is a huge hit of the family. We have had it with beef roasts, steaks and Pork Roasts. All fabulous! I have melted butter in a cast iron pan and then laid my potatoes on it to provide a crispness. It was fabulous.

    This is our go to and I greatly appreciate you sharing! Your recipe has been shared to so many of our friends and family!

    Your cookbook is also my go-to present for white elephants gift exchanges and birthday gifts with a bottle of wine.

    Christie

  9. HOLY GOODNESS was this so darn good! The family polished every bit of this away. I did sub emmanthal for the gruyere. This will be a staple dish for now and forever!

  10. We made this with beef tenderloin on Christmas Day. It was a huge hit and will now be our go to potato gratin recipe! Super easy and absolutely delicious!!

  11. Can’t wait to try this!! I am making it for our neighborhood monthly cookbook share. This month we are featuring all recipes from your cookbook!! Love everything I see and am flipping between this and the Chicken Chili Verde!! Which one should I make and bring!!

  12. I made these for Christmas on a whim. The family literally took spoons after the meal was done and finished it off. They were so darn good, and we’re making again in a few weeks for easter. Ya’ll this WILL NOT disappoint ! Spoil your family and loved ones with this recipe!!

  13. Hi Gaby,

    If you were making this ahead and par-baking it, how long would you bake for? I was going to make it the night before… Thanks!

    Nicole

    1. I don’t usually – if they start to get too brown, you could cover for the remainder of the time

  14. 5 stars
    Can’t wait to make this recipe for Christmas!! Also really hoping I win the set of all clad pots. Extra credit for commenting here, right? Haha Happy holidays!!

  15. Hi Gaby!
    This recipe sounds and looks delicious! I plan to make it on Christmas Eve for family. This serves 8-10, right? We’re only serving 4 people. Would this recipe still turn out great if it was split to serve 4?

    Thanks!!!

  16. 5 stars
    I just made these to take to a friends home for dinner, along with Prime Rib. These potatoes were the star of the meal. As good as or better than the high end steakhouses. Is it the Gruyere, caramelizing the onion or the combo of cream and cheeses? Whatever it is, these are the bomb.com. The only change I made was used mascarpone instead of crime fraiche as per the suggestions. It was not difficult And I will make them again for sure. They also traveled well. An hour in the car and no need to reheat.

  17. 5 stars
    This was on our Thanksgiving menu and will be there in years to come. It was excellent. The gruyere cheese made it. I did have some clear grease floating on the top. Not sure where that came from.

  18. Love this update on a classic!
    Would you mind sourcing the pan? I’ve been looking for something with short handles and love the look of the one in the photos.
    Thanks!

  19. I see in an older comment you recommend partially baking if making ahead of time. For how long would you do this? Wanting to make the day before.

  20. I will need to double this for 12 people. Can I do both recipes in one pan(layering all potatoes on bottom and pour all cheese on top?)
    Oven real estate is prime on Christmas
    Help!

  21. Hi – I’ve never used creme fraiche in my cooking before. Is this something you buy at the store or you make ahead of time? Do you have a recipe for this? I’ve seen a few different versions online. Thank you!

  22. 5 stars
    Just made this gratin today. It was fabulous. My husband and I ate half the dish. Will be making this for my family in Arizona when we go out there after Christmas. I couldn’t get Creme Fraiche so I had to use sour cream and it was still wonderful.

  23. Hi!
    YUM! Do you have a recipe for Prime Rib? I have a 10.5 LB boneless rib roast. I have not clue to how to cook it. I am going to do the potatoes and Brussels salad for the sides.

  24. Going to make this for Christmas! One question – I’m wondering if tossing the sliced potatoes in the cream & cheese mixture before layering them in the pan would be a good move or an unnecessary step? Any thoughts would be appreciated!!!

  25. I’m feeling frustrated & perplexed, Gaby. I made this twice this week – once for elderly family under quarantine yesterday and once for my family today – both dishes were extremely brown by 30minutes and totally scorched by 1 hour. I followed your directions to a T both times, and they were baked in both an electric and a gas oven – is 400* correct? I was so looking forward to this dish and got really nice gruyere. What happened?

    1. 400 is correct! but some ovens run hot – so if that happens again and the potatoes aren’t cooked through, you could cover it with foil to avoid it from browning on top but still allowing the potatoes to cook through

  26. This menu came just in time! I will be short oven space, how do you feel about making these potatoes in a crock pot?

    1. 5 stars
      I made this for Christmas dinner as an accompaniment to beef tenderloin with red wine sauce. I may have received the most compliments ever from my husband and we’ve been married 36 years! Thanks for a wonderful recipe.

  27. 5 stars
    Yum!!!! I used Havarti and mascarpone rather than gruyere and crème fraiche as that’s what I had on hand (apparently my fridge was feelin’ fancy). It turned out great! I will put foil on for half of the bake next time as it did get a little dark, but it wasn’t burnt. The taste was amazing. The family now refers to this recipe as the “gourmet cheesy potatoes”! Now I’m wondering if this could be used with pasta rather than potatoes for a mac and cheese situation? Fingers crossed for the #WGCChallenge! Thank you for sharing!

  28. I lost what happens to the onions. Leave them in the pan when you add cream and cheeses? I don’t see onions in the top of the potatoes from pouring the mixture over the top of them.

  29. Gaby,
    Wildly into menu planning for a turkey-less dinner.
    Committed to Duck breast, Mushroom Bread Pudding, Miso honey brussels sprouts, arugula anchovy salad, some kind of cranberry sauce and here’s the 64k question:

    Gaby’s Potatoes Au Gratin or your Sweet Potato Gratin (or??????)
    Does the bread pudding do battle with the white potatoes? What do you think?
    Ask Poppy?
    Best wishes to you and yours!
    Susie

  30. 5 stars
    Made these TWICE for Thanksgiving and Friendsgiving and they were excellent! The cheesy, decadent dish you want for the holidays!

  31. I see that you can make a day ahead, can you make two days ahead and still apply the par-bake method? Thanks and happy holidays!

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