This amazing sweet potato gratin has fresh herbs, lots of gruyère cheese, and prosciutto. Its sweet and savory flavors are perfect for the holidays.

A baking pan with sweet potato au gratin and two gold serving utensils.

My favorite holiday dishes are always au-gratins and stuffing. Don’t really care for the turkey as long as I have those two. Like everyone, I wait all year for the holiday dinner when all my favorites are gathered together on the table.

My love for sweet and savory notes makes this au-gratin is the best of both worlds. It is definitely more savory than your traditional, marshmallowy sweet potato casserole. It pairs really well with the traditional Greek turkey stuffing.

Close up of sweet potato au gratin with prosciutto and fresh herbs on top.

Are sweet potatoes au-gratin the same as scalloped sweet potatoes?

Well, I think they are very close, like sisters 🙂 The difference between scalloped sweet potatoes and sweet potatoes au-gratin is whether you use grated cheese or not. Potatoes au gratin has cheese, and scalloped sweet potatoes do not; they use heavy cream or milk. Also, scalloped potato slices tend to be thicker than au-gratin.

A baking pan with sweet potato au gratin and a gold serving utensil and a piece served on a green plate.

How to make this au-gratin

This sweet potato casserole has lots of grated Gruyère cheese and 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.

I lightly simmer heavy cream with minced garlic, cloves, fresh herbs, and nutmeg to use between the layers of cheese and sweet potatoes. While the cream simmers, it fills the whole house with the most delicious aroma that reminds me of Christmas custard.

Ingredients

  • Sweet potatoes
  • Gruyère cheese
  • Prosciutto cubetti
  • Butter 
  • Heavy cream
  • Fresh sage and thyme
  • Cloves
  • Garlic
  • Ground nutmeg
  • Eggs 
  • Sea salt
  • Freshly ground pepper

Detailed measurements and instructions can be found on the recipe card at the bottom of the page.

Sauce pan with cream, fresh herbs and spices.

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 thru a sieve to strain herb sprigs and cloves.

Eggs being beaten and adding cream to them.

In a large bowl, lightly whisk the eggs. Slowly pour the cream into the eggs. Keep whisking while pouring. Mix well. Set aside.

Four images. One, a buttered pan. Two, the pan with a layer potatoes and egg, cheese, herbs, prosciutto mix. Three, similar layer as two. Four, final layer of potatoes, cheese, egg and prosciutto.

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.

A half baked sweet potato au gratin before going back to the oven.

Remove foil, sprinkle top with remaining grated Gruyère.

Bake until nicely browned and bubbling for 25-30 minutes.

A sweet potato casserole and two serving utensils.

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A sweet potato casserole

Sweet Potato Gratin with Gruyère & Prosciutto

by Jenny | The Greek Foodie
A rich, cheesy, sweet potato gratin with sage and thyme is sweet, savory & perfect for Thanksgiving.
4.95 from 18 votes
Print Recipe
Prep Time 20 minutes
Cook Time 1 hour 10 minutes
Course Dinner, Holidays
Cuisine International
Servings 8
Calories 443 kcal

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
  • 1 teaspoon ground nutmeg
  • 1 tablespoon fresh thyme leaves
  • 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 thru 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 1/3 of the egg mixture—top potatoes with 1/2 cup Gruyère and 1 tablespoon of prosciutto.
  • Repeat with another layer of potatoes, a small pinch of salt and freshly ground pepper and 1/3 egg mixture. Top again with 1/2 cup Gruyère and 1 tablespoons of prosciutto.
  • Top with the last layer of potatoes, a small pinch of salt and fresh ground pepper, and the remaining egg mixture. Top again with 1/2 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

Nutritional Info – Please keep in mind that nutritional information provided is only an estimate and can vary based on products used.

Nutrition

Calories: 443kcalCarbohydrates: 15gProtein: 13gFat: 37gSaturated Fat: 22gCholesterol: 185mgSodium: 263mgPotassium: 304mgFiber: 2gSugar: 3gVitamin A: 9425IUVitamin C: 4mgCalcium: 384mgIron: 1mg
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Sweet Potato Gratin with Gruyère and Prosciutto

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22 Comments

  1. 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.

    1. 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

  2. 5 stars
    Two of our favourite things… Sweet potato and gratin!!

    Can’t wait to try this out, thanks for sharing.

  3. 5 stars
    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.

  4. 5 stars
    Oh my goodness, this looks really good and tasty, I will definitely add this dish in our menu list. Thank you!

  5. 5 stars
    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.

  6. 5 stars
    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!

  7. 5 stars
    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!

  8. 5 stars
    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!

  9. 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!

  10. 5 stars
    Omg!! Made this for dinner tonight and its amazing!!! We loved it so much – will definitely be making it again!!!

    1. 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

  11. 5 stars
    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!