A sweet and savory twist on a classic, this Sweet Potatoes au Gratin recipe is sure to steal center stage at your holiday or Thanksgiving table! Thin slices of sweet potatoes are coated in a creamy Gruyere cheese sauce, loaded with TONS of herbs and spices, and finished with a crunchy breadcrumb topping that’s irresistible. Easily meal prep this the day before and pop it in the oven when you’re ready to eat!
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Never have I ever seen a dish SO fancy, SO full of flavor, and secretly not TOO complicated to make!
Most of us have had au gratin with white potatoes (Yukon gold potatoes or Russet potatoes) but this version is on another level.
What started with a little inspo from these Scalloped Potatoes and Cauliflower Gratin quickly transformed into this burst of Fall flavors.
Sweet potato perfection.
Ingredients
For the exact measurements and detailed instructions, you can jump to the recipe.
- Sweet potato. There are several varieties available at grocery stores. Try to grab ones that are generally the same size so they can be cut into similar-shaped pieces that cook evenly.
- Butter. Unsalted butter is needed, but you can sub in coconut oil or olive oil, if needed.
- Milk. Both regular milk and a plant-based alternative will work. The key is to have it at room temperature.
- Cheese. Gruyere cheese and cheddar cheese, both shredded, are sprinkled on top of the potatoes. You’ll also want some Parmesan cheese for the topping.
- Seasonings. Along with salt and pepper, this recipe calls for fresh thyme, rosemary, and ground nutmeg.
- Breadcrumbs. Regular, unseasoned Panko breadcrumbs make the base of the crispy topping. You can grab a gluten-free variety from the grocery store, as well.
How to Make Sweet Potatoes au Gratin
Jump to the recipe for the full instructions, ingredient amounts, and a printable recipe.
- Prep the potatoes. Clean the potatoes by rinsing them under cold running water. Use your hands or a rag to scrub them until no visible dirt or debris remain. Dry each one off with a clean dish towel. Then, carefully slice the potatoes into ⅛-inch pieces. The best way to do this is with a mandolin slicer. But you can also use a very sharp chef’s knife.
- Line the potatoes. Spray a 9×13-inch baking or casserole dish with a non-stick cooking spray. Layer half of the potato slices across the bottom of the dish. Then, sprinkle ½-teaspoon salt and ¼-teaspoon of black pepper evenly over the top. Carefully place the rest of the slices in the pan, and top with the remaining salt and pepper.
- Make the sauce. Add the butter to a medium saucepan, and melt it over medium heat. Then, add the minced garlic and sauté for 30 to 60 seconds. Turn the heat down to medium-low and sprinkle the flour over the melted butter. Whisk immediately. It should form a thick paste.
- Add the milk and cheese. Then, pour in ¼-cup of the room temperature milk, being sure to whisk it well. After it thickens, add another ¼-cup at a time until it has all been mixed in and the sauce is smooth. Remove the pot from the stove and stir in the Gruyere cheese, cheddar cheese, fresh herbs, nutmeg, and remaining salt. Stir until the sauce is thoroughly combined.
- Coat the potatoes and bake. Carefully pour the creamy sauce on top of the sweet potatoes in the baking dish. Use a spatula to spread it out so all of the slices are coated. Cover the dish with a piece of aluminum foil, then bake in the preheated oven for 30 minutes.
- Add the crumb topping. While the potatoes are baking, add 1 tablespoon of melted butter, ¼-cup Panko crumbs, and ¼-cup Parmesan cheese to a medium bowl. Whisk until it is well combined. After the 30 minutes, remove the foil from the baking dish and sprinkle the crumb topping evenly over the potatoes. Bake for another 15 to 20 minutes. It is done when the topping is golden brown and the potatoes can easily be pierced with a fork. Serve with some fresh rosemary and thyme!
FAQs
While both scalloped and au gratin potatoes are a savory and creamy side, the main difference is the inclusion of cheese in au gratin. Both of these recipes are a perfect side dish for a holiday table or even a weeknight.
Gratin simply means to top with cheese, butter, and breadcrumbs and cook until crispy. You can use this method with a variety of foods, like in this Cauliflower au Gratin or these Brussels Sprouts au Gratin!
What to Serve with Sweet Potato Au Gratin?
This surprisingly simple dish goes well with just about any protein! Try any of these recipes alongside it.
If you’re a fish lover, try Blackened Mahi Mahi or Blackened Salmon.
You can also serve it with Chicken Cordon Bleu, Baked BBQ Chicken, or Caprese Chicken.
More Sweet Potato Recipes
If you prefer sweet potatoes over regular, you’re in luck. These easy recipes are sure to please your taste buds.
Another fun twist is Sweet Potato Shepherd’s Pie.
At Thanksgiving, whip up some Sweet Potato Casserole and Sweet Potato Pie.
And you can’t get easier than Air Fryer Baked Sweet Potato or Mashed Sweet Potato.
Learn How Healthy Sweet Potatoes are!
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Sweet Potatoes Au Gratin Recipe
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Ingredients
- 3 lbs. sweet potatoes cut into ⅛” slices
- 2 tsp. salt divided
- ½ tsp. black pepper
- 2 Tbsp. butter salted
- 2 Tbsp. flour all purpose or gluten-free 1-to-1 blend
- 4 cloves garlic finely minced
- 1 ½ cups milk regular or plant-based, room temperature.
- 1 cup Gruyere Cheese shredded
- 1 cup cheddar Cheese shredded
- 1 tsp. each of thyme and rosemary fresh
- ¼ tsp. nutmeg ground
Panko Parmesan Topping:
- 1 Tbsp. butter melted
- ¼ cup Panko crumbs or regular breadcrumbs
- ¼ cup Parmesan Cheese
Instructions
- Preheat the oven to 375 degrees.
- Prepare the Potatoes: Rinse and scrub the potatoes to remove any visible dirt. Dry thoroughly using a dish towel. Carefully cut the sweet potatoes into ⅛” slices using either a mandoline or a sharp chef’s knife.3 lbs. sweet potatoes
- Lay Potatoes in Baking Dish: Spray a 13×9-inch baking dish with non-stick cooking spray. Layer half of the sliced sweet potatoes in the bottom of the dish, sprinkle with ½ teaspoon salt and ¼ teaspoon of black pepper. Top with the remaining slices and another ½ teaspoon salt and ¼ teaspoon of black pepper2 tsp. salt, ½ tsp. black pepper
- Whisk the Sauce: Add the butter to a medium-sized saucepan over medium heat. Wait for it to melt before adding in the minced garlic cloves. Saute for 30-60 seconds, or until fragrant. Reduce heat to medium-low and sprinkle in the flour. Begin whisking immediately. Once it forms a thick paste, pour in ¼ cup of the room temperature milk, whisking well. When it thickens up, whisk in another ¼ cup of the milk and continue this process until all of the milk has been used and the sauce is smooth.2 Tbsp. butter, 2 Tbsp. flour, 4 cloves garlic, 1 ½ cups milk
- Mix in Cheese and Herbs: Remove the pot from the heat and add in the Gruyere cheese, cheddar cheese, fresh herbs, nutmeg, and remaining 1 teaspoon of salt. Whisk until the cheese is completely melted.1 cup Gruyere Cheese, 1 cup cheddar Cheese, 1 tsp. each of thyme and rosemary, ¼ tsp. nutmeg
- Cover and Bake: Pour the cheese sauce over the sliced potatoes in the baking dish, spreading it out using a spatula so all of the slices are coated. Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes.
- Add Crumb Topping: While the potatoes are baking, toss together the crumb topping ingredients in a medium-sized bowl until well combined. Remove the foil from the dish and sprinkle the crumb topping evenly over the potatoes. Continue baking for an additional 15-20 minutes, or until the topping has browned slightly and the potatoes are fork tender.1 Tbsp. butter, ¼ cup Panko crumbs, ¼ cup Parmesan Cheese
- Serve sweet potatoes au gratin immediately with a sprinkle of finely chopped fresh rosemary and thyme.
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Notes
- Storage: Keep leftovers in an airtight container in the refrigerator for up to 4 to 5 days.
- Potatoes: Cut them equally thin so they cook at the same rate.
- Topping: Don’t add the breadcrumbs right away or they’ll burn.
- Cheese: You can sub a dairy-free cheese if necessary, or choose a different variety.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
