Cheesy Sweet Potato Gratin Recipe - Fork Knife Swoon (2024)

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A cheesy sweet potato gratin Here’s what you’ll need to make this gratin Other cozy comfort foods to cook next: Sweet Potato Gratin Description Ingredients Instructions Equipment Leave a Rating or Reply 38 comments on “Sweet Potato Gratin” FAQs References

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★★★★★8 reviews

In this simple, cheesy sweet potato gratin recipe, sweet potatoes, gruyere, cheddar, garlicky cream, and fresh thyme come together to create a delicious twist on the classic potato au gratin casserole. Vegetarian and gluten free.

Cheesy Sweet Potato Gratin Recipe - Fork Knife Swoon (1)

A cheesy sweet potato gratin

I would almost always choose sweet potatoes over regular potatoes, and this sweet potato gratin – a vibrant, seasonal twist on the classic potatoes au gratin casserole – is no exception.

It’s a simple recipe: layers of sliced sweet potatoes baked until bubbly in a garlicky cream sauce with a triple dose of cheesy goodness and fresh herbs; at its heart cozy comfort food that’s perfect for holiday entertaining and sure to become a seasonal favorite.

Cheesy Sweet Potato Gratin Recipe - Fork Knife Swoon (2)

Here’s what you’ll need to make this gratin

This rich and cheesy sweet potato gratin combines mostly simple pantry ingredients with a couple of seasonal additions. Here’s what you’ll need to make it:

  • sweet potatoes: of course! We’ll use vibrant sweet potatoes in place of traditional yellow potatoes. For the best texture, be sure to slice them very thin, no more than 1/8” thick.
  • cheese: a blend of gruyére, sharp cheddar, and parmesan cheeses add tons of flavor, lots of creamy goodness, and forms the gratin or “crust” of the dish as it bakes.
  • olive oil and garlic: the flavorful base of the creamy sauce.
  • cream: for a rich and fully indulgent sauce that binds the scalloped sweet potatoes together.
  • thyme and nutmeg: for cozy, earthy fall flavor.
  • salt and pepper: be sure to season to taste!

Find all the exact measurements and full recipe instructions below.

Admittedly, slicing the potatoes takes a little bit of time (a mandoline is quite helpful for this), but after that, things come together quickly, and the gratin emerges from the oven golden and glorious and worth every ounce of effort. Happy cooking!!

Cheesy Sweet Potato Gratin Recipe - Fork Knife Swoon (3)

Other cozy comfort foods to cook next:

  • Simple homemade chicken ramen
  • Lemony kale and white bean soup
  • Pasta with broccoli and chicken sausage
  • Butternut squash noodle soup
  • Spinach and ricotta stuffed shells

If you make this sweet potato gratin recipe, be sure to tag me on Instagram with the hashtag #forkknifeswoon and leave a comment and rating below letting me know how you liked it! ★★★★★ Star ratings are especially helpful because they help others find my recipes too. xo, Laura

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Cheesy Sweet Potato Gratin Recipe - Fork Knife Swoon (4)

Sweet Potato Gratin

★★★★★4.9 from 8 reviews

  • Author: Laura Bolton – Fork Knife Swoon
  • Prep Time: 20 mins
  • Cook Time: 50 mins
  • Total Time: 1 hour 10 minutes
  • Yield: 4–6 Servings 1x
  • Category: Side Dish, Savory, Dinner, Holiday
  • Method: Baking
  • Cuisine: American, French
  • Diet: Vegetarian
Print Recipe

Description

In this simple, cheesy sweet potato gratin, sweet potatoes, gruyere, cheddar, garlicky cream, and fresh thyme come together to create a delicious twist on the classic potato casserole.

Ingredients

Scale

  • 2 lbs sweet potatoes, peeled
  • 1 cup grated Gruyére cheese
  • 1/2 cup grated sharp cheddar cheese
  • 1/4 cup grated Parmesan cheese
  • 1 tsp olive oil
  • 1 Tbsp fresh garlic, finely minced
  • 1–1/2 cups heavy cream or half-and-half
  • 4 sprigs fresh thyme, removed from stems and finely chopped
  • 1/2 tsp ground nutmeg
  • Kosher salt and freshly-ground black pepper, to taste

Instructions

  1. Preheat the oven to 375℉. Lightly grease a 9-inch baking dish with butter or nonstick baking spray. Set aside.
  2. Using a mandoline, carefully slice the sweet potatoes horizontally into thin rounds, no larger than 1/8” thick. Place the sweet potato slices in a single layer in an overlapping pattern in the baking dish.
  3. Set aside 1/2 cup of Gruyére cheese. Sprinkle the sweet potatoes with a third of the remaining Gruyére, cheddar, and Parmesan cheeses. Repeat with two more layers of potatoes and cheese.
  4. Meanwhile, heat the olive oil to a medium sauce pan over medium heat until shimmering. Add the garlic, and cook, stirring occasionally, until golden and fragrant, about 5 minutes.
  5. Add the cream, nutmeg, and thyme, and bring to a simmer. Cook, stirring often, until slightly thickened, about 5 minutes. Season with salt and pepper, to taste. Do not let come to a boil.
  6. Stir in the reserved 1/2 cup of Gruyére cheese, until melted. Slowly pour the warm cream mixture over the sweet potoates, letting it sink in amongst the layers. Top with a bit of fresh thyme leaves.
  7. Bake until the gratin is golden brown and bubbly and the potatoes are tender, about 45-50 minutes. If the gratin begins to brown too quickly, cover loosely with aluminum foil, as needed.
  8. Remove from the oven and let rest for 10-15 minutes before serving. Garnish with more fresh thyme. Enjoy!!

Keywords: sweet potato gratin, sweet potato casserole, potato gratin, garlic and thyme, gruyere cheese, sweet potato gratin with gruyere, au gratin, sweet potatoes, vegetarian, gluten free

Originally published on December 11, 2012. Updated photos by Jenn Davis added November 2018.

See Also
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posted by Laura on December 11, 2012 (last updated July 16, 2022)

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38 comments on “Sweet Potato Gratin”

  1. Mary Workman — Reply

    Any other cheesss besides Gruyere, family is not a fan!

    • Laura — Reply

      Hi, Mary! I might try gouda, or just go with all sharp cheddar. Enjoy!!

  2. Christine Balascoe — Reply

    Can this be made with Yams instead of sweet potatoes?

    • Laura — Reply

      Hi, Christine! I haven’t tried using yams, but I would think they should work. They are starchier than sweet potatoes, so the baking time may vary slightly. They key is to slice them super thin, and then just bake until bubbly and fork tender. Enjoy!!

  3. Donna — Reply

    I was wondering if this recipe could be made ahead and frozen for a short time then thawed and reheated?

    • Laura — Reply

      Hi, Donna! I haven’t tried freezing these potatoes. Generally, scalloped potatoes are okay to freeze but I don’t want to steer you wrong! However, you can definitely make them a couple of days in advance, cover tightly and refrigerate, and then reheat in the oven when ready to serve. Enjoy!!

      • Donna — Reply

        Thank you. I think I will make a day or two ahead. I may try freezing a small portion just to test it out!

        • Laura — Reply

          Thanks, Donna! Please let me know how it turns out! 🙂

  4. Rachel — Reply

    Does the recipe call for 0.5 Cups of Heavy Cream or 1.5 Cups if making the single recipe?

    • Laura — Reply

      Hi, Rachel! For the standard recipe you’ll need 1.5 cups. Enjoy!!

  5. Margaret — Reply

    Can I use cream hcheese along with the heavy cream

    ★★★★★

    • Laura — Reply

      Hi, Margaret! I haven’t tried adding cream cheese so I’m not sure exactly how it would turn out. That would definitely make it super rich! Please let me know your results 🙂 Enjoy!

  6. PJ — Reply

    Can’t wait to try this with the locally-grown sweet potatoes I just got, and the thyme from my garden (the only herb I seem to be able to grow). My kids, their SA’s, and my grandson are all foodies, so they will be good taste-testers. Thanks!

    • Laura — Reply

      Enjoy! Thanks, PJ!

  7. Kristy — Reply

    Smash hit of Christmas lunch. Fabulous sweet potato recipe. Decadent and delicious.

    ★★★★★

    • Laura — Reply

      Oh, yay! Thanks so much, Kristy!!

  8. Kate — Reply

    Hi! Can I make this. A day ahead and not bake it? Or would you suggest I bake it and reheat the next day?

    • Laura — Reply

      Hi Kate! I haven’t tried making it in advance without baking, but you can definitely bake it and reheat the next day. I would reheat at 350℉ covered with foil until it’s warmed through then uncovered for the last few minutes. Enjoy!!

  9. Michelle — Reply

    This looks so delicious! Question – if I double the recipe, would you suggest I make it in 2 separate 9 in baking dishes, or should I combine it into a larger dish?

    • Laura — Reply

      Hi Michelle! So you definitely can make it in two separate dishes. I worry a little about the potatoes cooking evenly in a larger dish (I haven’t tested it). I would try a 9×13 and be ready to cover with foil and/or turn the oven down (350℉?) for the second half of baking/cook for slightly longer in case the top starts browning before the potatoes are fully cooked through. Enjoy!!

  10. Amy — Reply

    This recipe is delicious. We scrapped the pan. I substituted sage instead of thyme. Really, really good.

    ★★★★★

    • Laura — Reply

      Thanks so much, Amy!!

  11. Helen — Reply

    Excellent. Followed recipe exactly using half-and-half instead of heavy cream. Don’t omit the fresh thyme. Wonderful flavors.

    ★★★★★

    • Laura — Reply

      Thank you so much, Helen!!

  12. Amy Westerman — Reply

    I love this recipe and have made it a few times. Is it something that can be made a day ahead?????

    ★★★★★

    • Laura — Reply

      Hi Amy! So happy you love the recipe! Yes, you can make it the day before (or morning of), and reheat in the oven when ready to serve. Happy Thanksgiving!!

  13. Janace — Reply

    I made this for a potluck at my church today and I got a ton of compliments! I think I’ll probably make it for Thanksgiving dinner this year as well. Thanks for the great recipe, love the blog!

    ★★★★★

    • Laura — Reply

      This is one of our favorites for Thanksgiving too 🙂 Thanks, Janace!

  14. Karla — Reply

    What size Casserole dish would be suitable for this dish?

    • Laura — Reply

      Hi Karla! I’d recommend a 9-inch square or oval baking dish for this gratin. Enjoy!

  15. Brandi — Reply

    So yummy!

    • Laura — Reply

      Thanks, Brandi!!

  16. Tamie — Reply

    This gratin is specially requested by family and friends for the past 3 years. It is absolutely delicious!

    ★★★★★

    • Laura — Reply

      Thanks so much, Tamie! Happy Thanksgiving!!

  17. Stacy — Reply

    Made this tonight for Thanksgiving. It looks and taste great!! I will serve it tomorrow

    ★★★★

    • Laura — Reply

      Thank you so much, Stacy! So glad you enjoyed the recipe! It’s one of my favorite dishes to serve for guests at the holidays…

  18. Erica — Reply

    I don’t know what I did wrong, but mine turned into a groopy, oily mess. The cheese didn’t melt despite bubbling like crazy, and there was this oily goo through the whole dish. Bummer, because I was hoping to love this recipe!

    • Laura — Reply

      Erica, I am so sorry to hear that! I’ve made this recipe many times without anything like that happening… usually the cheese begins to melt even as I pour the warm cream mixture over the sweet potato layers. My only thought it that it could possibly be an issue with the specific brand(s) of cheese used? Alternatively, you could try melting the cheese completely in the cream mixture while it is on the stove, and then pouring that over the layered potatoes…

Leave a comment »

Cheesy Sweet Potato Gratin Recipe - Fork Knife Swoon (2024)

FAQs

Do you stab sweet potatoes before baking? ›

Do you have to poke holes in sweet potatoes before baking? Typically holes are poked into a sweet potato to prevent a potato exploding in your oven. However, the chance of that happening is low, and according to Lifehacker, sweet potatoes will retain more flavor if you don't poke them.

Learn More Now ›
How do you keep sweet potato casserole from being runny? ›

Eggs and cream help stabilize the dish and prevent it from becoming too runny (a common complaint with many sweet potato casserole recipes). Make it as smooth or chunky as you like!

See More ›
How to tell when sweet potato casserole is done? ›

Sprinkle the topping evenly over the sweet potato mixture, then pop it into the oven and let it bake for 40 to 45 minutes. You will know it's done when the topping is lightly browned and the center of your casserole is set and firm.

Explore More ›
How do I thicken up my sweet potato casserole? ›

If it cooks, but doesn't thicken enough, you can make up a slurry of cornstarch & cold water & mix that in (before putting on the marshmallow topping). Let it cook a bit longer for the heat to activate the cornstarch & thicken it, then add your topping.

Get More Info ›
What happens if you don't stab a potato before baking it? ›

"Yes, it's good to prick them," Smith told Food52. "It pokes holes in the skin, which allows steam to escape. Otherwise, they could explode—it doesn't happen all the time, but it happens every once in a while. The potato is full of water it's trying to turn to steam, or water vapor.

Get More Info Here ›
What happens if you don't pierce potatoes before baking? ›

Do you poke holes in potatoes before baking? We actually don't poke holes in our potatoes before baking! It is said that poking holes in the potato allows steam to escape the potato so it doesn't explode, but in reality, steam is actually able to escape from the skin (and we've never experienced a potato explosion!).

Explore More ›
Why put egg in sweet potato casserole? ›

The egg is the all-important binder in a sweet potato casserole: it enriches and stiffens the mixture without making it heavy. Make sure to cool the mash slightly before adding the egg so it doesn't scramble, and to stir well so there are no streaks of cooked egg white in the finished dish.

Read The Full Story ›
Why are my sweet potatoes still hard after baking? ›

If the potato is still firm when squeezed, that means it needs to cook more. Baked sweet potatoes can be stored in an airtight container in the refrigerator for up to 5 days. Reheat for 2 minutes in the microwave, at 400°F in the air fryer for 5 minutes, or at 400°F in the oven for 10 minutes.

Continue Reading ›
Can you eat sweet potato casserole left out overnight? ›

Once they've been cooked, however, they should go in a shallow airtight container or zip-top bag in the fridge. They'll stay good there for about five days. Tip: You shouldn't leave cooked sweet potatoes at room temperature for more than two hours, as this can promote bacteria growth and cause foodborne illness.

Learn More ›
How long is it safe to eat sweet potato casserole? ›

To Store: Store sweet potato casserole covered in the refrigerator for 4-5 days. To Freeze: Prepare the sweet potato casserole completely, but don't bake it. Cover with a double layer of aluminum foil and freeze for up to 3 months.

Get More Info Here ›

Is sweet potato casserole supposed to be jiggly? ›

Sprinkle the pecan topping mixture over the top of the sweet potato filling. Bake the casserole for 35 to 45 minutes, until the filling is hot, does not jiggle when you shake the dish, and the topping has browned.

Explore More ›
Why is my sweet potato casserole soupy? ›

Boiled sweet potatoes have a tendency to absorb water, which, in turn can make the casserole a little soupy. This recipe, however, calls for baking the sweet potatoes! You'll also find that this recipe doesn't add too much liquid to the mix.

Keep Reading ›
Can you overcook a sweet potato? ›

If your sweet potatoes cook too long in the oven they can overbake and become dry. The insides will become mushy. Moving your sweet potato cubes around and checking them periodically can help avoid overcooking.

Show Me More ›
Should you poke holes in sweet potatoes before baking them? ›

Before baking, use a fork to prick each sweet potato several times. You don't need to jab the fork in deep. We're creating steam vents. Otherwise the pressure in the sweet potato could build up so high in the oven that it explodes—an unlikely possibility but one best avoided!

Show Me More ›
Why do you pierce sweet potatoes before baking? ›

Pierce the sweet potato with a fork or sharp knife in several places, about about 6 times. This will allow steam to escape from the potatoes while they bake. Place your clean (and jabbed) sweet potatoes on the prepped baking sheet.

Read The Full Story ›
Do you stab potatoes before putting them in the oven? ›

The golden rule of baked potatoes? Always prick your spud! The old adage of them exploding under the pressure of oven heat is actually true. As the potato cooks, the skin acts as a seal, trapping water that expands the spud and steams during cooking.

Learn More ›
Why do you soak sweet potatoes before baking? ›

The cold water bath helps rinse the starch off the sweet potatoes so they're a bit more crispy. That said, if you do not have the time, you can still get crispy baked sweet potato fries by using high heat and a little drizzle of olive oil.

Learn More ›

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