Creamy, Cheesy, Sweet Potato Au Gratin Recipe

5 from 1 vote
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An easy, cheesy, sweet potato take on a November classic! This Sweet Potato Au Gratin replaces white potatoes with sweet potatoes, adds fresh herbs and aromatics, and three kinds of cheeses for a delicious, oven-baked potato casserole that will be gobbled up in no time! 

overhead shot of a sweet potato au gratin casserole topped with fresh thyme

What Makes This Recipe Great

Sweet potato casseroles are all the rage during Thanksgiving. While I absolutely love the classic ooey, gooey marshmallowy brown sugar yams, I wanted to create something cheesy, savory, and different this year. Enter, Sweet Potato Au Gratin

This cozy side dish features sliced sweet potatoes, a garlic-infused cream sauce, and a three-cheese mixture of gruyere, parmesan, and gouda! Plus, a little fresh thyme for a burst of flavor. The resulting comfort food dish is so good I guarantee you will not have any leftovers. But if you do, they taste just as good the next day! 

I love how the savory additions balance the sweetness of the potatoes– truly my new favorite way to eat sweet potatoes! 

And if sweet potato recipes are your thing, try my amazing Chicken Bacon Ranch Stuffed Sweet Potatoes, these Fries, or these Sliders

Ingredients Notes

recipe ingredients on a white surface and labeled.
  • Sweet potatoes: For best results, cut into 1/8 inch slices on mandolin slicer. If you don’t have a slicer, use a sharp knife and cut into thin slices. 
  • Heavy cream
  • Garlic
  • Unsalted butter
  • Gruyere cheese
  • Gouda cheese
  • Parmesan cheese
  • Fresh Thyme
  • Salt and black pepper to taste 

How to Make Sweet Potato Au Gratin

numbered step by step photos showing how to prep the tomatoes and cream sauce
numbered step by step photos showing how to assemble the casserole
  1. Preheat your oven to 375°F
  2. 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.
  3. Layer the sliced sweet potatoes in a greased baking dish. Season each layer with salt/pepper and thyme, sprinkle with the cheese 3 different types of cheese.
  4. 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.
  5. Sprinkle the remaining cheese mixture over the top of the dish.
  6. Cover the baking dish with aluminum foil and bake for about 45 minutes.
  7. 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
a sweet potato au gratin casserole up close to show the melted cheese

Mac’s Pro TipS

Expert Tips

  • Dairy-Free/Vegan: If you’re dairy-free or vegan, feel free to swap out the heavy cream, butter, and cheese for vegan alternatives. Silk makes a dairy-free heavy cream that would work well. Use vegan butter and a mixture of dairy-free cheese shreds and/or nutritional yeast. Let me know if you make it this way and how it turns out! 
  • Make-Ahead: If you have a busy day ahead, feel free to make this dish ahead of time– up to 48 hours in advance. Complete steps 2-5, then cover and refrigerate until you’re ready to serve it. Preheat your oven, let the casserole sit out for about 30 minutes to get to room temperature, then bake according to steps 7 and 8. 
  • Regular Potatoes: Feel free to swap out the sweet potatoes for Yukon gold potatoes or Russet potatoes. It won’t have the natural sweetness from the sweet potatoes, but it will be a savory, delicious side dish nonetheless. 

Serving Tips

Serve alongside your Thanksgiving dinner spread of stuffing, turkey, green beans, and more! Or make for an easy side dish for a weeknight or weekend family dinner! 

Storage Tips

Store leftovers in an airtight container for up to 3-4 days. Reheat individual portions or bake at 350F for 20 minutes or until warmed through. 

a serving spoon resting inside a sweet potato au gratin casserole.

Recipe FAQs

What is au gratin vs scalloped potatoes?

Scalloped potatoes have the same creamy sauce but typically don’t contain cheese, while au gratin potatoes have both the creamy sauce and the added cheese. The cheese is the secret to au gratin’s gooey, rich, and slightly different flavor and texture compared to its scalloped counterpart.

What is the difference between au gratin and gratin?

They’re essentially the same cooking technique. “Gratin” is the more general term for browning a dish’s top layer, while “au gratin” specifically refers to the use of cheese and often breadcrumbs in creating that delicious, golden crust on top of a dish. In this case, sweet potato gratin and sweet potato au gratin are completely interchangeable! 

Is it okay that the cream mixture is not thick when adding over the sweet potatoes?

The cream mixture might seem thin when poured over the sweet potato slices initially. However, as the casserole cooks, the starch from the sweet potatoes works its magic, thickening the sauce. Don’t worry if the cream isn’t thick at first—it transforms into something amazing by the end of the cooking process.

scooping sweet potatoes out of a baking dish.

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Creamy, Cheesy, Sweet Potato Au Gratin Recipe

5 from 1 vote
An easy, cheesy, sweet potato take on a November classic! This Sweet Potato Au Gratin replaces white potatoes with sweet potatoes, adds fresh herbs and aromatics, and three kinds of cheeses for a delicious, oven-baked potato casserole that will be gobbled up in no time! 
Prep Time: 10 minutes
Cook Time: 45 minutes
Total Time: 55 minutes
Servings: 12

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, sprinkle with the cheese 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

    • The cream mixture might seem thin when poured over the sweet potato slices initially. However, as the casserole cooks, the starch from the sweet potatoes works its magic, thickening the sauce. Don’t worry if the cream isn’t thick at first—it transforms into something amazing by the end of the cooking process.
    • Dairy-Free/Vegan: If you’re dairy-free or vegan, feel free to swap out the heavy cream, butter, and cheese for vegan alternatives. Silk makes a dairy-free heavy cream that would work well. Use vegan butter and a mixture of dairy-free cheese shreds and/or nutritional yeast. Let me know if you make it this way and how it turns out! 
    • Make-Ahead: If you have a busy day ahead, feel free to make this dish ahead of time– up to 48 hours in advance. Complete steps 2-5, then cover and refrigerate until you’re ready to serve it. Preheat your oven, let the casserole sit out for about 30 minutes to get to room temperature, then bake according to steps 7 and 8. 
    • Regular Potatoes: Feel free to swap out the sweet potatoes for Yukon gold potatoes or Russet potatoes. It won’t have the natural sweetness from the sweet potatoes, but it will be a savory, delicious side dish nonetheless. 

Serving Tips

Serve alongside your Thanksgiving dinner spread of stuffing, turkey, green beans, and more! Or make for an easy side dish for a weeknight or weekend family dinner! 

Storage Tips

Store leftovers in an airtight container for up to 3-4 days. Reheat individual portions or bake at 350F for 20 minutes or until warmed through. 

Nutrition

Calories: 306kcal | Carbohydrates: 13g | Protein: 11g | Fat: 24g | Saturated Fat: 15g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 6g | Trans Fat: 0.1g | Cholesterol: 76mg | Sodium: 306mg | Potassium: 264mg | Fiber: 2g | Sugar: 4g | Vitamin A: 8884IU | Vitamin C: 4mg | Calcium: 332mg | Iron: 1mg

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

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About Me

Mother, wife, cookbook author, recipe creator an open book

Welcome to Healthy Little Peach. I’m Mac, the lady behind the recipes. I believe in living a healthy lifestyle that consists of a mix of healthy whole foods, and full-fat comfort meals. Life is too short not to enjoy good food while maintaining a healthy body and mind. Here you will find gluten-free, dairy-free, paleo, keto, and even full-fat comfort recipes. Let’s have fun in the kitchen together!

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Recipe Rating




2 Comments

  1. 5 stars
    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.