If you’ve ever made au gratin potatoes only to end up with watery sauce or undercooked slices, you’re not alone. I tested and tweaked this recipe until it consistently delivers tender layers of sweet potato baked in a rich, creamy cheese sauce. The result is perfectly seasoned, velvety, and reliably delicious — ideal for Sunday dinners, holiday spreads, or anytime you want a comforting side dish.
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This is classic comfort food — not a health-food recipe, but one you’ll reach for during holidays (hello, Thanksgiving) or when you want to treat yourself. If you enjoy layered, cheesy bakes, you might also like my scalloped corn, scalloped potatoes, or zucchini au gratin recipes, which share similar flavors presented in different ways.
Sweet Potatoes Au Gratin Ingredients
- Sweet potatoes
- Butter
- Garlic
- Cream cheese
- Heavy cream
- Cheddar cheese
- Parmesan cheese
- Mozzarella cheese
- Onion powder, salt, and pepper
How to Slice the Potatoes
I prefer slicing sweet potatoes into 1/4-inch rounds for even cooking; 1/2-inch rounds also work. A mandolin gives uniform slices, which helps ensure the potatoes cook through evenly and the dish finishes without excess liquid.
How to Make Sweet Potato Au Gratin
Detailed measurements and the full recipe card are included below. In summary, the process is straightforward and designed to prevent watery sauce and ensure tender potatoes.
- Preheat oven to 350°F (175°C).
- Heat a saucepan over medium heat and melt the butter.
- Add minced garlic and cook for a couple of minutes until fragrant.
- Stir in cream cheese, heavy whipping cream, grated Parmesan, and 1/2 cup shredded cheddar. Season with onion powder, salt, and pepper, and taste to adjust seasoning.
- Stir continuously until the cheeses melt and the sauce is smooth.
- Arrange the sliced sweet potatoes in rows in a 9×13 baking dish and drizzle the cheese sauce evenly over them.
- Sprinkle the remaining 1/2 cup cheddar and the mozzarella over the top.
- Cover with foil and bake 30 minutes, then remove foil and bake an additional 25 minutes until the potatoes are tender.
- Optional: For a crisp, browned top, broil for 1–3 minutes a couple of minutes before the dish is done.
- Let cool about 30 minutes before serving so the sauce firms up slightly.
Sweet Potato Au Gratin
Brandi Crawford
Pin Recipe
Equipment
- 9×13 baking dish
- Mandolin slicer (optional for uniform slices)
Ingredients
- 2 pounds sweet potatoes, sliced into 1/4- or 1/2-inch rounds
- 1 tablespoon butter
- 2 garlic cloves, minced
- 4 oz cream cheese
- 1/4 cup heavy whipping cream
- 1 cup shredded cheddar cheese, divided (use 1/2 cup in the sauce and 1/2 cup for topping)
- 1/4 cup shredded Parmesan Reggiano
- 1 teaspoon onion powder
- Salt and pepper to taste
- 1/2 cup shredded mozzarella
Instructions
- Preheat oven to 350°F (175°C).
- Heat a saucepan over medium heat and add the butter.
- When the butter melts, add the garlic and cook until fragrant, about 1–2 minutes.
- Add the cream cheese, heavy cream, Parmesan, and 1/2 cup cheddar. Stir in onion powder, salt, and pepper. Taste and adjust seasoning as needed.
- Stir continuously until the cheese melts and the sauce is smooth, then remove from heat.
- Arrange sweet potato slices in rows in a 9×13 baking dish and drizzle the cheese sauce evenly over them.
- Sprinkle the remaining 1/2 cup cheddar and the mozzarella across the top.
- Cover with foil and bake 30 minutes. Remove the foil and bake an additional 25 minutes, or until the sweet potatoes are tender.
- For a crisp top, broil 1–3 minutes at the end of baking until the cheese browns slightly.
- Let cool about 30 minutes before serving to allow the sauce to set.
Notes
- To reduce fat, use low-fat cream cheese and lower-fat cheeses, or reduce the amount of cheese used.
- This dish can be assembled a day ahead. Press plastic wrap close to the potatoes to minimize discoloration, refrigerate, and bake before serving. Top slices may brown slightly overnight.
- Freezing is possible though dairy may separate on thawing; reheat in a 350°F oven until warmed through.
Nutrition
Nutrition is an estimate and can vary depending on the exact ingredients used. For accurate tracking, calculate using your preferred nutrition tool and the brands you use.
Frequently Asked Questions and Recipe Pro Tips
Both are creamy, casserole-style potato dishes. Scalloped potatoes typically use a milk- or cream-based sauce without grated cheese, while au gratin includes grated cheese and often a browned or breadcrumb topping. You can achieve a crisp top for au gratin by broiling the finished dish briefly.
In most U.S. grocery stores the terms are used interchangeably, but true yams are a different, starchier tuber with rougher skin and are less common in typical U.S. markets. Most recipes labeled ‘yams’ in the U.S. are actually sweet potatoes.
A blend of cheddar, Parmesan Reggiano, and mozzarella creates a balance of flavor, saltiness, and meltiness. Using block cheese and grating it yourself yields the best melting texture compared with pre-shredded cheeses that contain anti-caking agents.
This is a savory preparation of sweet potatoes. It highlights salty, cheesy flavors rather than the sweet versions that use sugar, cinnamon, or marshmallows.
Yes. Assemble, cover tightly, and refrigerate up to a day before baking. Press plastic wrap close to the potatoes to reduce discoloration. Bake before serving; the top may brown slightly but the sauce and baking will blend everything together.
Store tightly covered in the refrigerator for 3–4 days.
Dairy-based casseroles can be frozen, though the texture may change on thawing. If freezing, reheat in a 350°F oven until warmed through; some separation may occur but the dish remains tasty.
More Sweet Potato Recipes
Southern Candied Sweet Potatoes
Southern Sweet Potato Casserole
Sweet Potato Beef Chili
Air Fryer Sweet Potato Fries
Healthy Sweet Potato Pie
Healthy Sweet Potato Fries
Sweet Potato Cornbread
Mashed Sweet Potatoes with Brown Sugar
Pair this au gratin with homemade creamed corn and a baked ham for a classic holiday plate.
Check out a variety of authentic soul food recipes on the original site for more inspiration.