Sweet Potato Gratin is a fresh and flavorful twist on a classic French dish. It has layers of fluffy sweet potatoes baked in cream, Gouda and Parmesan cheese, and fresh thyme. This simple recipe is a favorite for the holidays and weeknight dinners alike!
Thanksgiving side dishes are always my favorite part of the holiday spread. Of course, I love a beautiful roasted turkey, but the sides are what I really look forward to. This sweet potato gratin is great because it is full of flavor. It also looks beautiful in a baking dish, making it a showstopper.
Tell Me About Sweet Potato Gratin
Ultra Flavorful: This recipe is similar to traditional potatoes au gratin but with a more complex flavor from the sweet potatoes and herbs.
Simple Ingredients: You only need a few basic ingredients to make the most creamy and rich sweet potato gratin you’ll ever try.
Easy Recipe: You can bake and serve it in the same dish, which means fewer dishes and easy cleanup.
Key Ingredients
Along with the sweet potatoes, you’ll need just three main components: cheese, cream, fresh herbs, salt and black pepper.
Olivia’s Prep Tips
Thin, even slices of sweet potato are the key to this recipe. I slice the potatoes to 1/8-inch thick. So, I like to use a mandolin slicer to take the guesswork out of this step. Just be sure to use the guard to protect your fingers and don’t go *too* fast.
If you don’t have a mandolin, you can still get nice even layers with a knife. You’ll want to use a very sharp knife (carefully!) and take your time, but it works just fine. Don’t forget to peel it before.
Assemble Your Sweet Potato au Gratin
First: Combine the milk and cream in a mixing bowl and set it aside.
Second: Place a single layer of sweet potato slices in a greased baking dish or a casserole dish.
Then: Pour the cream mixture, add salt, pepper, thyme, and grated cheese. Repeat this process with the rest of the ingredients, creating about 6-8 layers.
Finally: Gently press the layers down to completely submerge the sweet potatoes in the cream and top it with extra cheese. Bake your au gratin potatoes for 45 minutes.
Give These Simple Variations A Try
Cheese: Gouda and parmesan cheese are my favorites in this dish. Other good choices include gruyère cheese, havarti, sharp cheddar cheese, and asiago.
Herbs: Feel free to use other fresh herbs like rosemary, sage, thyme, or a mix of a couple of different herbs.
Veggies: You can easily sub sweet potatoes for regular white potatoes or golden potatoes. Or, try my cauliflower au gratin that’s just as rich.
How To Make It Ahead Of Time
If you’re making this recipe for the holidays, it’s a great side dish to prep in advance. Here are a few time-saving steps you can take:
Pre-slice the sweet potatoes and store them in cold water in the fridge for up to 2 days. Just be sure to pat them very dry before using them. You can also pre-shred your cheese up to a week ahead of time so it’s ready to go.
If you want to prep the whole dish, you can assemble the layers the night before. Then, bring it to room temperature and pop the baking dish in the oven when you’re ready.
Storage & Reheating
Once the leftovers cool, you can either over the baking dish or transfer them to an airtight container. Then, store it in the fridge for up to 4 days. When you’re ready to reheat, warm the leftovers in the oven or microwave until they heat through.
Popular Sweet Potato Sides
Sweet Potato Gratin
Equipment
Ingredients
- 3 sweet potatoes peeled and sliced about ⅛ inch thick.
- Kosher salt and freshly ground pepper
- 1.5 teaspoons fresh thyme roughly chopped
- ¾ cup parmesan cheese shredded
- 1 ¾ cups Gouda or Mozzarella shredded
- 1/2 cup milk
- 1/2 cup heavy cream
Instructions
- Set the oven to 400°F and lightly grease a cast iron skillet or a round baking dish.
- Mix the cream and milk together in a bowl and set aside.
- Spread the sweet potatoes in an even layer in your casserole dish, baking sheet, or skillet. Pour a few tablespoons of the cream mixture over the top, then season with salt, pepper, and thyme, and sprinkle with a little cheese.
- Repeat the process with the remaining potatoes and cream, seasoning each layer as you go, until you have 6–8 layers. Gently press down so the potatoes are fully coated in the cream mixture, and add extra cheese on top if you like.
- Cover the skillet or baking dish with foil and bake for 30 minutes. Then uncover and bake for another 30–45 minutes, or until the cream is absorbed, the potatoes are tender, and the top is golden brown.
- Remove from the oven and let it rest for 15 minutes before serving.
Notes
- Be sure to let your sweet potato gratin rest before serving. This lets the sauce thicken, which holds the dish together.
- You can turn the broiler on for the last couple of minutes to get an extra golden and bubbly top. Just keep a close eye on it, as the broiler works quickly.
- I recommend freshly shredded cheese vs pre-shredded for the smoothest texture.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
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