Sweet Potato Au Gratin (Creamy & Cheesy Holiday Side)
Published Nov 06, 2023 Updated Nov 28, 2025
This post may contain affiliate links. Please read our disclosure policy.
If you’re dreaming up a holiday side dish that feels special without asking too much of you, this sweet potato au gratin is the kind of Thanksgiving side that brings cozy, cheesy comfort to any gathering! It has all the charm of a classic gratin with melty Gruyère, a golden brown top, and slow-baked tenderness, but with the natural sweetness of sweet potatoes that makes every bite feel warm and memorable. This savory, cheesy twist on the sweet potato dishes I grew up loving fits right in on any holiday table!
Table of Contents
Why You’ll Love This Recipe
This sweet potato au gratin is the kind of cozy comfort food that shines during Thanksgiving, Christmas, or any chilly fall evening. Thinly sliced sweet potatoes are layered with a simmered cream sauce and three cheeses, creating tender texture, even layering, and an irresistible, golden cheesy crust!
It feels elegant enough for a holiday spread yet fits perfectly beside turkey, stuffing, greens, or my Easy Maple Glazed Carrots. If you love the classic sweet potato casserole style but want something more savory and unexpected, this dish stands out without stealing the spotlight.
For a complete holiday lineup, serve this dish alongside my Southern Green Beans (Keto, Whole30), my Old-Fashioned Cornbread Dressing Recipe, or The Best Creamy Mashed Potatoes.
Ingredients You’ll Need
- Sweet potatoes: Slice them about 1/8 inch thick. A mandoline slicing tool is best for uniform pieces, but a sharp knife works too. Thinly sliced potatoes help the layers cook evenly.
- Heavy cream: Creates the base of your simmered cream sauce, which thickens as the sweet potatoes release starch during baking.
- Butter: Adds richness and helps carry the garlic flavor throughout every layer.
- Garlic: Brings warm, savory depth to the sauce.
- Gruyère: Helps create that cheesy sweet potato bake texture everyone loves.
- Gouda: Makes the sauce extra creamy and helps it cling to every potato slice.
- Parmesan: Adds a salty, sharp finish to balance the sweetness of the potatoes.
- Fresh thyme: Provides an herby brightness that cuts through the richness.
- Salt and pepper: Essential for seasoning every layer so the flavor stays consistent top to bottom.
Dairy-Free or Vegan Options: Use dairy-free cream (like Silk), vegan butter, and dairy-free cheese shreds or nutritional yeast. The texture will vary slightly, but the results will still be creamy and savory.
How to Make Sweet Potato Au Gratin
Step 1: Preheat your oven to 375°F. Peel sweet potatoes.
Step 2: Using a mandoline or a sharp knife, slice the potatoes about 1/8 inch thick. Make sure to slice the potatoes as evenly as possible.
Step 3: In a saucepan, melt the butter over medium heat. Add the garlic and cook until fragrant. Stir in the heavy cream and season with salt and pepper. Heat for a few minutes – the mixture will look thin at first.
Step 4: Shred the cheeses. For the creamiest melt, grate the Gruyère, Gouda, and Parmesan by hand.
Step 5: Layer sweet potato slices in a greased baking dish. Season each layer with salt, pepper, and thyme.
Step 6: Pour a small amount of the cream mixture over each layer, just enough to lightly coat the potatoes. Sprinkle with the cheeses.
Step 7: Aim for 3-4 layers. Add the remaining cheese on top.
Step 8: Cover with foil and bake for 45 minutes. Remove the foil and bake 15-20 minutes more, until the potatoes are tender and the top is golden brown and bubbling. Enjoy!
Mac’s Pro TipS
Expert Tips & Troubleshooting
- If your cheese sauce looks grainy, the cream mixture got too hot. Keep the heat gentle when warming the cream so the dairy doesn’t separate before baking.
- Don’t worry if the cream mixture seems thin when you pour it in. As the dish bakes, the starch from the sweet potatoes thickens the sauce naturally.
- Slice the potatoes evenly for the best texture. Uneven slices can bake at different speeds.
- If the top browns too quickly, loosely tent the dish with foil.
- A watery gratin in other recipes usually comes from too much liquid per layer. This method avoids that by keeping layers lightly coated, not drenched.
Make-Ahead & Storage
This recipe is a true make-ahead casserole, which is a lifesaver on busy holidays!
- If you want to make this dish ahead of time just assemble it up to 48 hours ahead, cover, and pop it in the fridge. Let it warm on the counter for 30 minutes, then bake as directed.
- Store leftovers in an airtight container for 3-4 days. Reheat individual portions in the microwave or warm the full dish at 350°F for about 20 minutes.
Recipe FAQs
If your sweet potatoes stayed firm, they were likely sliced too thick or the layers were packed too tightly. Thin, even slices help the heat circulate so the tender layered potatoes soften fully during baking.
Excess liquid or thick potato slices can cause a watery texture. Thin slices create a tender, cohesive final dish.
Totally up to you! Peeling creates a softer texture, but leaving the skin on works too.
Yes! This recipe is written for a standard 9×13 baking dish, but it also works in a deep 9×9 pan. A smaller, deeper dish adds a few extra minutes to the total bake time, while a wider dish may finish slightly faster. You’ll know it’s done when the potatoes are fully tender and the center is bubbling.
More Holiday-Inspired Recipes
By Course
Whole30 + Keto Thanksgiving Turkey
Side Dishes
Cheesy Brussels Sprouts Gratin Recipe
Appetizers & Snacks
Easy Cranberry Turkey Sliders with Hawaiian Rolls
If you love this sweet potato au gratin recipe, please give it a star rating and leave a comment below! Follow me on Pinterest, Facebook, and Instagram for more!
Sweet Potato Au Gratin (Creamy & Cheesy Holiday Side)
Ingredients
- 3 sweet potatoes cut into 1/8 inch slices on mandolin slicer
- 1 3/4 cups heavy cream
- 4-5 cloves garlic minced
- 2 tbsp unsalted butter melted
- 1 1/2 cup gruyere cheese shredded
- 1/2 cup Gouda shredded
- 1/2 cup parmesan cheese shredded
- 2 tbsp fresh thyme
- salt and pepper to taste
Instructions
- Preheat your oven to 375°F
- In a saucepan, melt the butter over medium heat. Add the minced garlic and cook for a minute or two until fragrant—add in the heavy cream and season with salt and pepper. Heat for a couple of minutes. (This mixture will not be super thick. But the sauce gets thicker as it cooks due to the potato starch).
- Layer the sliced sweet potatoes in a greased baking dish. Season each layer with salt/pepper and thyme, and sprinkle with the 3 different types of cheese.
- Pour the cream mixture over each layer of the sliced sweet potatoes, ensuring that the potatoes are well coated. I usually do 3-4 layers. Make sure not to add too much to each layer.
- Sprinkle the remaining cheese mixture over the top of the dish.
- Cover the baking dish with aluminum foil and bake for about 45 minutes.
- Remove the foil and bake for an additional 15-20 minutes, or until the sweet potatoes are tender, and the top is golden brown and bubbling
Notes
Expert Tips & Troubleshooting
- If your cheese sauce looks grainy, the cream mixture got too hot. Keep the heat gentle when warming the cream so the dairy doesn’t separate before baking.
- Don’t worry if the cream mixture seems thin when you pour it in. As the dish bakes, the starch from the sweet potatoes thickens the sauce naturally.
- Slice the potatoes evenly for the best texture. Uneven slices can bake at different speeds.
- If the top browns too quickly, loosely tent the dish with foil.
- A watery gratin in other recipes usually comes from too much liquid per layer. This method avoids that by keeping layers lightly coated, not drenched.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
I made this over the weekend for a dinner party and it was AMAZING!!! So So good. I highly recommend. The only thing is the heavy cream isn’t listed on the steps. I realized this in the process so I just added it to the pan with the butter & garlic, brought it to a boil and took it off of the burner. It wasn’t thick but it still baked up great.
Thank you Wendy! You added the cream at the right time. I’m so glad it was a hit. Thanks for trying!
This was AMAZING ! So easy and delicious. I swear I heard angels singing when I tasted it !
I’m so happy you enjoyed it. Happy Thanksgiving!
Delicious! We got a bunch of sweet potatoes from the farmer’s market, so we needed a way to use a LOT of sweet potato, and this perfect. We didn’t modify it in any way. Cutting the sweet potatoes with a mandoline was a bit difficult (I think our blade is not sharp enough), but the recipe is so good that we’ll keep it anyway. 🙂