This post may contain affiliate links. Please read our disclosure policy.
This sweet potato gratin is a comforting and easy holiday side dish. My recipe layers tender, seasoned sweet potato slices with Gruyère cheese in a rich, creamy sauce, baked until bubbly and golden. It steals the show whenever I serve it at Christmas or Thanksgiving dinner!
Like my cauliflower gratin, this sweet potato gratin turns a humble veggie into the most delicious holiday side dish. I layer thinly sliced sweet potatoes in a creamy sauce with savory herbs and seasonings. Baked in the oven, the sauce is warm and bubbly, and the potatoes caramelize underneath a layer of topping of melted Gruyère and Parmesan cheese. It’s the BEST! Serve it with this year’s Thanksgiving turkey or a Christmas glazed ham.
Reasons You’ll Love This Cheesy Sweet Potato Gratin
- Full of cozy flavor. Brimming with sweetness from the potatoes and freshly grated cheese, I love the contrast of flavors and textures in this dish. It’s next-level!
- A lighter version of a classic. My sweet potato au gratin uses evaporated milk instead of heavy cream. It has all the comfort of a classic gratin without the heaviness.
- Make it ahead. This sweet potato side dish is great to prepare ahead of time. It allows flavors to meld and frees up oven space for other dishes at the holidays!
Ingredients You’ll Need to Make This Recipe
Au gratin recipes are similar to scalloped potatoes. While cheese is optional in scalloped potato recipes, it’s a key ingredient in potatoes au gratin!
Below are some notes on the ingredients you’ll need for this easy sweet potato gratin. Scroll to the recipe card for the full recipe amounts.
- Sweet Potatoes – These should be thinly sliced. A mandolin slicer makes this step quick and easy; otherwise, do your best to slice the potatoes to the same thickness. This way, they’ll bake evenly.
- All-Purpose Flour – Helps thicken the sauce for a creamy consistency. You could replace the flour with cornstarch. In this case, you’ll need half the amount of cornstarch as flour.
- Seasonings – I season my potatoes with a mix of ground ginger, nutmeg, paprika, dried rosemary, and thyme, plus salt and pepper. You can replace the dried herbs with fresh if you’d like. Use 3 times the amount of fresh herbs as dried.
- Evaporated Milk – I love using a can of evaporated milk for convenience, and as a lighter alternative to heavy cream in my potatoes au gratin. Make sure you’re using unsweetened evaporated milk, and not sweetened condensed milk. If you’d prefer to use heavy cream for an even richer sauce, that’s fine, too!
- Parmesan Cheese – Freshly grated is best.
- Gruyère Cheese – You might recognize Gruyère from French onion soup recipes. It’s a mild, melty cheese with a nutty flavor. You can substitute Swiss cheese or grated cheddar if needed.
Can I Make This Recipe With Regular Potatoes?
Yes! If you’d prefer a traditional potato gratin, you can use Yukon Gold or russet potatoes in place of sweet potatoes in this recipe. Slice them thin and follow the recipe as directed.
Recipe Tips and Variations
- Slice the potatoes evenly. For even cooking, make sure to cut the sweet potatoes to a uniform thickness. Use a mandolin if you have one for consistent slices.
- Master the layering technique. When layering the sweet potatoes in the dish, slightly overlap the slices. This way, there won’t be any gaps.
- Try different cheeses. Feel free to experiment with different types of cheese. Like the Swiss and Parmesan cheese I use in this recipe, a mix of sharp and mild cheeses works nicely. Try Provolone, Grana Padano, Gouda, sharp cheddar, Havarti cheese, etc.
- Add a breadcrumb topping. For extra crunch, add a breadcrumb and Parmesan topping or a cracker topping like I do in my cheesy potatoes recipe.
- Make it spicy. Add heat with crushed chili flakes or cayenne pepper.
- Add ham. Make a version of ham potato au gratin and layer cooked and diced ham or bacon in between the sweet potatoes.
What to Serve With Sweet Potato au Gratin
Serve this sweet potato gratin as a side to air fryer rotisserie chicken on a weeknight. Or, enjoy it with tender pork loin or a juicy beef tenderloin for a cozy winter dinner. It’s also a star at our Thanksgiving dinner, paired with more favorite sides like green bean casserole, my traditional homemade stuffing, and cranberry sauce.
Pin this now to find it later
Pin It
Sweet Potato Gratin
Ingredients
- 2 pounds sweet potatoes, thinly sliced
- 2 tablespoons all purpose flour
- salt and fresh ground black pepper, to taste (I add about 1 teaspoon of salt and 1/2 teaspoon black pepper)
- ½ teaspoon dried thyme
- ½ teaspoon dried rosemary
- ½ teaspoon paprika or chili powder
- ¼ teaspoon ground ginger
- ¼ teaspoon ground nutmeg
- 1 can (12 ounces) evaporated milk
- ¼ cup grated parmesan cheese
- ½ cup grated swiss cheese or gruyere cheese
- grated parmesan cheese, for garnish, optional
- parsley, for garnish, optional
Instructions
- Prep for baking. Preheat oven to 350ºF. Lightly grease a 9-inch baking dish with butter or cooking spray and set aside.
- Season the sweet potatoes. In a large bowl, combine the sliced sweet potatoes, flour, salt, pepper, thyme, rosemary, paprika, ginger, and nutmeg; toss to combine.
- Assemble. Arrange one layer of sliced sweet potatoes, overlapping slightly, on the bottom of the baking dish. Sprinkle with a bit of parmesan and pour about 1/4 cup of evaporated milk. Repeat layers with remaining sweet potatoes, parmesan, and milk. Top with Swiss or Gruyère cheese.
- Bake. Cover with foil and bake for 35 minutes. Remove foil and continue to bake for 20 more minutes or until the top is browned and bubbly and the potatoes are tender.
- Cool, garnish, and serve. Remove from oven and let cool for 10 minutes. Garnish with grated parmesan and dried parsley, and serve!
Notes
- Sweet Potato Slices: Cut the slices to the same thickness for even cooking.
- Layering: Slightly overlap the sweet potato slices. This not only looks nice but ensures each bite is seasoned and flavored.
- Season Every Layer: Sprinkle each layer of sweet potatoes with a bit of the seasoning mix.
- Cheese Choices: Use different cheeses for varied flavors.
- Crunchy Topping: For some crunch, add a breadcrumb mix on top during the last few minutes of baking.
- Pre-Cooking Sweet Potatoes: If you’re short on time, parboil the sweet potato slices for a few minutes before baking. This reduces the overall cooking time in the oven.
- Herb Variations: While thyme is classic, sage can also complement sweet potatoes.
- Creamier Sauce: You can use heavy cream for an even creamier texture.
- Spice It Up: Add a pinch of cayenne pepper to the spice mix.
- Let it Rest: Allowing the gratin to rest for 10 to 15 minutes after baking helps the layers settle and makes it easier to serve.
Nutrition
Nutritional info is an estimate and provided as courtesy. Values may vary according to the ingredients and tools used. Please use your preferred nutritional calculator for more detailed info.
How To Make Sweet Potato Gratin
I’m convinced this is the best potatoes au gratin recipe ever, even better than regular potatoes au gratin! There’s something about the contrast of caramelized sweet potatoes and savory sauce that’s seriously unmatched. It’s very easy to prepare with about 10 minutes of prep:
- Prepare for baking. Preheat the oven to 350°F and grease a 9-inch baking dish with butter or cooking spray.
- Season the potatoes. Toss sliced sweet potatoes with flour, seasonings, and thyme in a large bowl.
- Arrange. Layer the sweet potatoes in the baking dish, same as you would for a scalloped potatoes recipe, sprinkling parmesan and drizzling evaporated milk between layers.
- Add cheese and bake. Top the potatoes with Swiss or Gruyere cheese, cover with foil, and bake for 35 minutes. Remove the foil and bake for an additional 25 minutes until browned and bubbly.
- Finish, then serve. Let the sweet potato gratin cool for 30 minutes, garnish with extra parmesan and dried parsley before serving.
Storing and Reheating Leftovers
- Refrigerate. Store any leftover sweet potato gratin in an airtight container in the fridge for up to 4 days.
- Reheat. Warm the gratin in the oven or in the microwave until the layers are hot throughout.
How yummy! This is a great twist on a classic! Can’t wait to try it
Never thought to make this with sweet potatoes and so glad I tried it! YUM!