This amazing sweet potato gratin has fresh herbs, gruyère cheese, and prosciutto. Its sweet and savory flavors are perfect for the holidays.
If you’re a fan of our delicious Sweet Potato Gratin, you’re in for a treat with our Fig Tart With Phyllo, Phyllo Cup Appetizers, and Roasted Cabbage with Bacon, Raisins, and Garlic!
Why this recipe sings
Here is what you need.
- Sweet potatoes—You can use any variety. A fun idea is to mix red sweet potatoes with purple ones for a colorful dish.
- Gruyère cheese—I love this nutty, slightly sweet cheese. I love the Cretan version of Gruyere called graviera.
- Prosciutto cubetti—I wanted to use prosciutto in this recipe because I love it so much. It usually comes very thinly sliced and is hard to cut into small uniform pieces. Prosciutto cubetti came to the rescue. It is pre-cut into perfectly sized pieces that are thick enough and ideal for this dish. Prosciutto cubetti is widely available in grocery stores and supermarkets. Substitute with pancetta or bacon.
- Butter— I always use salted butter unless the recipe specifies unsalted. You may use your favorite butter.
- Heavy cream— For a lighter au gratin, you may use half and half or milk.
- Eggs— fresh, organic, free-range eggs are always a great choice. You should get what is best within your budget.
- Fresh sage and thyme— The ultimate herbs of the season. Fresh are always better but dried versions work just as well.
- Cloves and ground nutmeg— Combined with the eggs and heavy cream they make the custard so aromatic, almost addictive!
- Garlic— A little goes a long way, adding flavor.
- Sea salt and freshly ground pepper.
Detailed measurements and instructions can be found on the recipe card at the bottom of the page.
How to make this sweet potato au gratin
Heat oven to 400 degrees.
In a medium pot, bring cream, a few sage leaves, cloves, a couple of thyme sprigs, minced garlic, ground nutmeg, and a pinch of salt to a simmer. Simmer until reduced a little, about 10 minutes. When the cream mixture is ready, pour it through a sieve to strain herb sprigs and cloves.
In a large bowl, lightly whisk the eggs. Slowly pour the cream into the eggs. Keep whisking while pouring. Mix well. Set aside.
Butter a 10.5″ X 7.5″ baking pan or gratin dish. Sprinkle some grated cheese all over the bottom of your pan. (Image 1)
Place a layer of potatoes in the pan, slightly overlapping as you go. Sprinkle a pinch of salt and freshly ground pepper over sweet potatoes. Pour 1/3 of the egg mixture. Top potatoes with about 1/3 cup Gruyère and 1 tablespoon of prosciutto cubetti. (Image 2)
Repeat with another layer of potatoes, a small pinch of salt and freshly ground pepper, and 1/3 egg mixture. Top again with another 1/3 cup cheese and 1 tablespoon of prosciutto cubetti. (Image 3)
Top with the last layer of potatoes, a small pinch of salt and fresh ground pepper, and the remaining egg mixture. Top again with 1/3 cup gruyère and 1 tablespoon of prosciutto. (Image 4)
Cover with a buttered foil sheet and bake until potatoes are tender about 40 minutes.
Remove the foil and sprinkle the top with the remaining grated Gruyère.
Bake until nicely browned and bubbling for 25-30 minutes.
What to serve with this sweet potato au gratin
- Roasted turkey thighs and our delicious Greek turkey stuffing.
- Arakas consists of sweet green peas cooked in olive oil with dill and spring onions. It’s a light and tasty side dish to the rich holiday table.
- This au gratin is not exclusive to the holidays! You can enjoy it all year with a large salad, turkey meatballs, short ribs, or lamb burgers.
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Cooked this? Rate this recipe! You can also leave a comment below. I love hearing from you!
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Sweet Potato Gratin with Gruyère & Prosciutto
Ingredients
- 6 medium sweet potatoes Sliced into 1/8-inch-thick rounds.
- 3 tablespoons butter softened
- 1.5 cups grated Gruyère cheese
- 4 oz prosciutto cubetti
- 2 cups heavy cream
- 3 tablespoons fresh sage chopped, or two teaspoon of dried sage
- 1 teaspoon ground nutmeg
- 1 tablespoon fresh thyme leaves or a teaspoon of dried thyme
- 3-4 cloves
- 4 garlic cloves minced
- 3 eggs lightly beaten
- salt
- freshly ground pepper
Instructions
- Heat oven to 400 degrees.
- In a medium pot, bring cream, a few sage leaves, cloves, a couple of thyme sprigs, minced garlic, ground nutmeg, and a pinch of salt to a simmer. Simmer until reduced a little, about 10 minutes.When the cream mixture is ready pour it through a sieve to strain herb sprigs and cloves.
- In a large bowl, lightly whisk the eggs. Slowly pour the cream into the eggs; keep whisking while pouring. Mix well. Set aside.
- Butter a 10.5" x 7.5" baking pan or gratin dish.Sprinkle grated cheese all over the bottom of your pan.
- Place a layer of potatoes in the pan, slightly overlapping as you go.Sprinkle a pinch of salt and freshly ground pepper over sweet potatoes. Pour 1⅓ of the egg mixture—top potatoes with ½ cup Gruyère and 1 tablespoon of prosciutto.
- Repeat with another layer of potatoes, a small pinch of salt, freshly ground pepper and ⅓ egg mixture. Top again with ½ cup Gruyère and 1 tablespoon of prosciutto.
- Top with the last layer of potatoes, a small pinch of salt and freshly ground pepper, and the remaining egg mixture. Top again with 1/2 cup Gruyère and 1 tablespoon of prosciutto cubetti.Cover with a buttered foil sheet and bake until potatoes are tender, about 40 minutes.
- Remove foil, sprinkle top with remaining grated Gruyère.Bake until nicely browned and bubbling for 25-30 minutes. Let au-gratin cool a little and serve.
Notes
Nutrition
Where is the prosciutto in the recipe? It’s not on the card and no mention of how to get individual tablespoons of prosciutto. Usually, prosciutto is cut very thin and so being able to measure a tablespoon would be very difficult.
Hi Benjamin,
Thank you for pointing that out, the recipe was updated recently and the prosciutto was left out by mistake. I use prosciutto cubetti which is pre-cut in small cubes /small slices, makes it easier to measure. I added a link for the product. I will put a note that a tablespoon is approximate.
Thank you again, hope you will enjoy the recipe.
x Jenny
Two of our favourite things… Sweet potato and gratin!!
Can’t wait to try this out, thanks for sharing.
Thanks so much, hope you will like it!
Flavorful. Nutmeg, Garlic and Herbs make a lovely combination. This dish looks creamy and cheesy and surely delicious. My weekend is going to be the best.
I didn’t know potato gratin could look so beautiful! This sounds divine!
Oh my goodness, this looks really good and tasty, I will definitely add this dish in our menu list. Thank you!
Turned out excellent. My brother loved it and asked for this recipe so he can make it again. I shared your page with him and now he’s a fan.
This recipe is amazing. Last night was actually the first time I made sweet potato gratin actually and I’m hooked! Before this I’d only made potato gratin. Oh and with this recipe I got to use my homegrown sage and thyme too. Just so delicious!
This gratin looks and sounds so flavorful! We would prefer it to the classic sweet version. The notes of Gruyère and prosciutto make it outstanding!
This is absolutely amazing! I make something similar every Christmas, but haven’t added prosciutto before. Definitely adding this to my holiday menu this year!
Hope you like it with prosciutto! Thanks so much!
I also wouldn’t care about turkey if I had this on my Thanksgiving table! Sounds like a great change from the usual scalloped potatoes. I love that you used prosciutto!
Thank you Erin!
This looks so tasty and easy to make! I can’t wait to try it out for Thanksgiving!
Hope you like it, Elena! Thanks so much, Jenny
Omg!! Made this for dinner tonight and its amazing!!! We loved it so much – will definitely be making it again!!!
Hi, Aline!
So happy you liked the au gratin.
Thank you! x Jenny
Can I make this ahead of time? Any instructions would be great!! this looks SOOOOOO GOOD!
Hi Kate!
It is really good!
You have two options:
1. You can prepare ahead, peel, and slice the potatoes the day before; store them in a ziplock bag in the fridge. You can simmer the cream mixture (don’t add the eggs) and grate the cheese the day before as well, storing them covered in the refrigerator. You assemble the rest the day of, bake as directed and serve.
2. Bake it for the first 40 minutes, let it cool, and refrigerate overnight. Next day let it come to room temp, add a couple of tablespoons of half and half or heavy cream on top and add grated cheese and reheat for about 40 minutes on a 350 F oven.
I will actually update the post and add these options, it’s a good idea.
Let me know how it came out!
Happy Holidays! x Jenny
Hi! This sounds amazing, I’ll be making this for tomorrow for Thanksgiving. Do I have to pre-cook the prosciutto cubetti Before adding it to the raw ingredients? Thank you!
Hi Nikki! You don’t have to precook the prosciutto, just use it as is. Happy Thanksgiving! X Jenny
Hello! Getting ready to make this for Thanksgiving. Can’t wait! I have a question… should the potatoes be peeled?
Hi Kathleen!
I leave the skin on and cut the sweet potatoes as thin as I can.
Thank you so much for making the gratin!
Let me know how it went.
Happy Thanksgiving!
x J