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!

A metal spoon is used to scoop sweet potato au gratin from a casserole dish.

Best Sweet Potatoes au Gratin Recipe

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 sweet potato 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.

Shredded Gruyere cheese, fresh thyme and rosemary, and a secret spice (I’ll give you a hint: it starts with a nut- and ends in a -meg!) give the creamy s​auce lots of depth.

But the real kicker comes in at the end. A Panko Parmesan breadcrumb topping counteracts those soft and tender potatoes with a crunchy and salty bite. Bonus—there’s no heavy cream so it’s better for you than many other recipes.

While there are a couple of steps involved, like making the cheese sauce and slicing the potatoes, you can easily prepare the entire dish the day before your big celebration and simply pop it in the oven.

Sweet potato au gratin ingredients include sweet potatoes, cream, cheese, butter, and herbs.
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The simple ingredients you need to make this delicious sweet potato au gratin recipe are:

  • 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.
  • Garlic. Freshly minced garlic creates a rich flavor that perfectly balances the sweetness of the potatoes.
  • Flour. You only need a little bit of flour for this recipe. You can either go with regular flour or a gluten-free 1 to 1 blend.
  • 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

Please see the recipe card below for ingredient amounts and more detailed instructions.

Prep the Potatoes

Preheat the oven to 375℉.

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 sweet 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.

Sliced sweet potatoes are spread across a casserole pan.

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.

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.

Cheese is added to make the sauce.

Coat 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.

The cheese sauce is spread across the sliced sweet potatoes.

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!

Sweet potato au gratin is prepared in a casserole dish.

What’s the difference between au gratin and scalloped potatoes?

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.

What does it mean to cook au gratin?

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!

Sweet potato au gratin is baked in a casserole dish.

Dietary Modifications

The recipe you’ll find below is already vegetarian as written. Here are some adjustments and substitutions you can make to help it fit your other dietary requirements:

  • Gluten-free: Opt for a gluten-free 1-to-1 blend of flour and gluten-free breadcrumbs.
  • Dairy-free: Choose a dairy-free cheese, butter, and milk variety.

Expert Tips and Tricks

  • Thin is key. Use a mandolin for the thinnest slices.
  • Layer it up. The process to building the au gratin is essential for maximum flavor.
  • You choose. It’s easy to sub in another variety of cheese or herbs to change it up.
  • Make it early. This is the perfect recipe to make a couple days ahead of time.
  • Get it crispy. Be sure to bake the dish uncovered at the end or even broil for a few minutes for a crunchy topping.

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 BleuBaked BBQ Chicken, or Caprese Chicken.

A fork digs into a big serving of sweet potato au gratin on a white plate.

More Sweet Potato Recipes

If you prefer sweet potatoes over regular, you’re in luck. These healthy and 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!

Tap stars to rate!

5 from 2 votes

Sweet Potatoes Au Gratin Recipe

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 herbs and earthy spice, and finished with a crunchy crumb topping that’s irresistible.
Yield 8 servings
Prep 30 minutes
Cook 45 minutes
Total 1 hour 15 minutes
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  • 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


  • 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 pepper
    2 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.
Last step! If you make this, please leave a review letting us know how it was!

Tap stars to rate!

5 from 2 votes



Meal Prep and Storage

  • How to prep ahead of time: You can slice the potatoes a couple of days before, just leave them in the fridge until you’re ready. Alternatively, completely assemble the dish, but save the breadcrumb topping. 
  • How to store: Keep leftovers in an airtight container in the refrigerator for up to 4 to 5 days.
  • How to freeze: While you can freeze this recipe, it’s best frozen without the topping. Be sure to completely cool before wrapping tightly and freezing for up to 6 months.
  • How to reheat: This dish is best warmed up in the oven at 350℉. You can use the microwave, but it will be mushy.


Calories: 372kcal, Carbohydrates: 44g, Protein: 14g, Fat: 16g, Saturated Fat: 9g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 4g, Trans Fat: 0.2g, Cholesterol: 46mg, Sodium: 903mg, Potassium: 643mg, Fiber: 6g, Sugar: 11g, Vitamin A: 24710IU, Vitamin C: 5mg, Calcium: 442mg, Iron: 2mg

Nutrition information is automatically calculated, so should only be used as an approximation.

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