Creamy, Cheesy Sweet Potato Gratin (video)

a large casserole with potato gratin, on a marble table

One of my favorite side dishes for the holiday season! I partnered with Reynolds Wrap® to bring you my creamy, cheesy sweet potato gratin recipe. It pairs perfectly with holiday turkey, duck or even ham. Reynolds Wrap® Heavy Duty Foil is a must in my kitchen, especially during the holidays!

I make my sweet potato gratin with a cheesy béchamel sauce seasoned with garlic, thyme and rosemary. Thinly sliced sweet potatoes are coated with the cheesy sauce, baked, then covered with more cheese. Every bite is bursting with incredible flavor and texture!

Watch My Potato Gratin Video Tutorial

Watch my YouTube sweet potato gratin video tutorial for step-by-step instructions and more tips! Want to stay up to date on the latest recipes? Make sure to subscribe to my website email list and my YouTube channel and turn on notifications.

Ingredients & Supplies for the Recipe

Here are my tips for the main ingredients and supplies you’ll need to make this recipe at home for the holidays. Find the full list of ingredients in the printable recipe card below.

  • Sweet Potatoes: this recipe also works great with regular potatoes. Go for large, classic orange sweet potatoes.
  • Reynolds Wrap® Heavy Duty Foil is a tough and durable foil which is perfect for lining your casserole dish for this recipe, since you don’t have to worry about it tearing or ripping. And, it makes cleanup a breeze!
  • Whole Milk & Cream: for making the creamy béchamel sauce. For an even richer version, use half milk and half cream.
  • Gruyere Cheese: this semi-firm, aged cheese adds an incredible savory flavor to the sauce, and it’s great for adding on top of the potatoes, too.
  • Parmesan Cheese
  • Thyme & Rosemary: fresh herbs will add the most aroma and flavor to the sauce. Dried herbs will work in a pinch, too. Just reduce the amount needed in half.
  • Garlic & Shallots: for making the sauce.

Sponsored by Reynolds Wrap®

This recipe post is sponsored by Reynolds Wrap®. Reynolds Wrap® is proudly celebrating 75 years this year, helping families make prepping, cooking and cleanup easier since 1947. I’ve been using their foil in my kitchen ever since I started cooking, and I can’t entertain without it during the holiday season.

Reynolds Wrap® Heavy Duty Foil is also available in a wider, 18-inch roll, which great for lining larger baking sheets and covering larger dishes.

a plate of food on a table, with a box

Preparing the Cheesy Béchamel Sauce

While this cheesy sweet potato gratin looks impressive, it’s easier to make than you think! I recommend starting with the cheesy béchamel sauce.

  1. Preheat a large sauté pan over medium heat and melt the butter in the pan. Add in the diced shallots and cook for 4 to 5 minutes, until the shallots are tender and translucent; don’t brown. Next, add in the garlic, thyme, and rosemary and cook for about 30 seconds.
  2. Sprinkle in the flour, toss until it’s absorbed into the butter, then cook for 1 minute. Beginning adding the milk, about ½ cup at a time. Whisk after each addition and cook until the sauce thickens before adding the next portion. Pour in the cream last.
  3. Season the sauce with salt, pepper, and a touch of freshly ground nutmeg. Allow the sauce to come up to a simmer over medium heat. Add 1 cup of parmesan cheese and 1 cup of gruyere cheese and cook just until the cheese is dissolved, about 1 minute.
  4. Cover the sauce with a lid, remove from the heat and keep it warm on the side.

Preparing the Sweet Potatoes

Once the béchamel sauce is ready and done, it’s time to prepare the sweet potatoes. I recommend preparing them after the sauce since they can brown easily.

  1. Peel the sweet potatoes, then rinse them with cold water to keep them from browning.
  2. Using a sharp, large knife or a mandolin slicer (my preferred method), slice the potatoes to 1/8-inch thickness. Make sure to use a cut glove whenever you use a slicer!

Keep the sliced potatoes in neat stacks on a separate tray. This will make the assembly much easier and quicker.

a close up image of a casserole filled with sweet potatoes

How to Make Cheesy Sweet Potato Gratin

Next, prepare an oven-safe casserole pan for baking the sweet potato gratin. Line the inside of a large oval, square, or round pan with Reynolds Wrap® Heavy Duty Foil. If needed, use two overlapping sheets to ensure the sauce doesn’t leak.

  1. Pour half of the prepared béchamel sauce into your lined casserole dish. Work with 10 to 15 slices of sweet potato at a time. Stack the potatoes neatly, then fan them slightly before arranging them in the pan.
  2. Watch my video tutorial to see how I arranged mine. Tuck any smaller pieces and ends of the sweet potatoes around the sides.
  3. Spoon the remaining sauce over the arranged sweet potatoes, ensuring they’re well covered. Cover the casserole dish tightly with another sheet of Reynolds Wrap® Heavy Duty Foil.

Baking Instructions for Gratin

Bake the gratin in a preheated oven set to 350°F for 1 to 1 and 15 minutes, until the sweet potatoes are cooked and very tender. Check for doneness using a knife or toothpick.

Remove the foil from the top and sprinkle the remaining ½ cup parmesan and ½ cup gruyere cheese on top. Switch the oven setting to broil, and broil on the ‘high’ setting for 5 to 8 minutes, until the cheese is melted and lightly browned.

a plate of food on a table, with potatoes and chicken

Serving Suggestions & Pairings for the Holidays

This creamy, cheese sweet potato gratin will be extremely hot coming out of the oven! Allow it to cool for about 30 minutes before enjoying. I love to serve it with roasted chicken, turkey, lamb chops, duck, or even ham. It’s a fantastic side dish for all your holiday main dishes!

Check out some of my favorite holiday recipes here:

  • Garlic Butter Turkey – a fan favorite for years! This recipe yields a super soft, flavor-packed and aromatic turkey every single time. Plus, it’s easy to prepare!
  • Holiday Duck Recipe – an easy but impressive recipe for holiday duck, stuffed with oranges, shallots and garlic.
  • Bacon & Apple Stuffed Pork Roulade – stunning stuffed pork tenderloin roll filled with bacon bits, apples, cranberries and more. This one is always a huge hit!
  • Maple Glazed Turkey – if you love all things maple, this incredible turkey recipe is for you! Brined in an apple cider brine, then glazed with maple syrup, this turkey is super juicy and flavorful!

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Creamy, Cheesy Sweet Potato Gratin (video)

30 minutes prep + 1 hour cook
8 servings
The best sweet potato side dish for the holidays! Sweet potato gratin is made with thinly sliced potatoes baked in a cheesy béchamel sauce!

Ingredients 

  • 3 tbsp butter
  • 2 large shallots, finely diced
  • 6 garlic cloves, finely minced
  • 1 tbsp fresh thyme
  • 1 tbsp fresh rosemary, chopped
  • 3 tbsp all-purpose flour
  • 2 cups whole milk
  • 1 cup heavy cream
  • 1 1/2 tsp sea salt
  • 1/2 tsp ground black or white pepper
  • 1/8 tsp freshly ground nutmeg
  • 1 1/2 cups grated parmesan cheese, divided
  • 1 1/2 cups grated gruyere cheese, divided
  • 5 to 6 medium sweet potatoes

Instructions

Making the Béchamel Sauce:

  • Begin with the sauce. Preheat a large sauté pan over medium heat and melt the butter in the pan. Add in the diced shallots and cook for 4 to 5 minutes, until the shallots are tender and translucent; don’t brown. Next, add in the garlic, thyme, and rosemary and cook for about 30 seconds.
  • Sprinkle in the flour, toss until it’s absorbed into the butter, then cook for 1 minute. Beginning adding the milk, about ½ cup at a time. Whisk after each addition and cook until the sauce thickens before adding the next portion. Pour in the cream last.
  • Season the sauce with salt, pepper, and a touch of freshly ground nutmeg. Allow the sauce to come up to a simmer over medium heat. Add 1 cup of parmesan cheese and 1 cup of gruyere cheese and cook just until the cheese is dissolved, about 1 minute.
  • Cover the sauce with a lid, remove from the heat and keep it warm on the side.

Preparing the Potatoes:

  • Peel the sweet potatoes, then rinse them with cold water to keep them from browning.
  • Using a sharp, large knife or a mandolin slicer (my preferred method), slice the potatoes to 1/8-inch thickness. Make sure to use a cut glove whenever you use a slicer!
  • Keep the sliced potatoes in neat stacks on a separate tray. This will make the assembly much easier and quicker.

Assembling the Gratin:

  • Preparing an oven-safe casserole pan for baking the sweet potato gratin. Line the inside of a large oval, square or round pan with Reynolds Wrap® Heavy Duty Foil. If needed, use two overlapping sheets to ensure the sauce doesn’t leak.
  • Pour half of the prepared béchamel sauce into your lined casserole dish. Work with 10 to 15 slices of sweet potato at a time. Stack the potatoes neatly, then fan them slightly before arranging them into the pan.
  • Watch my video tutorial to see how I arranged mine. Tuck any smaller pieces and ends of the sweet potatoes into the sides.
  • Spoon the remaining sauce over the arranged sweet potatoes, ensuring they’re well covered. Cover the casserole dish tightly with another sheet of Reynolds Wrap® Heavy Duty Foil.

Baking Instructions:

  • Bake the gratin in a preheated oven set to 350°F for 1 to 1 and 15 minutes, until the sweet potatoes are cooked and very tender. Check for doneness using a knife or toothpick.
  • Remove the foil from the top and sprinkle the remaining ½ cup parmesan and ½ cup gruyere cheese on top. Switch the oven setting to broil, and broil on the ‘high’ setting for 5 to 8 minutes, until the cheese is melted and lightly browned.
  • This creamy, cheese sweet potato gratin will be extremely hot coming out of the oven! Allow it to cool for about 30 minutes before enjoying. I love to serve it with roasted chicken, turkey, lamb chops, duck, or even ham. It’s a fantastic side dish for all your holiday main dishes!

Nutrition

Calories: 522kcal | Carbohydrates: 44g | Protein: 19g | Fat: 30g | Saturated Fat: 18g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 8g | Trans Fat: 0.2g | Cholesterol: 96mg | Sodium: 1100mg | Potassium: 787mg | Fiber: 6g | Sugar: 12g | Vitamin A: 25160IU | Vitamin C: 7mg | Calcium: 574mg | Iron: 2mg