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A creamy and delicious Sweet Potato Scalloped Casserole is shown as a tempting featured image for a recipe.

Sweet Potato Scalloped Casserole

This Sweet Potato Scalloped Casserole offers a delightful twist on the classic side dish. Tender sweet potato slices are layered in a creamy, savory sauce, topped with a golden, crispy breadcrumb topping. It's a comforting and flavorful casserole that's sure to impress.
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Prep Time 30 minutes
Cook Time 55 minutes
Total Time 1 hour 25 minutes
Servings: 8
Course: Side Dish
Cuisine: American
Calories: 450
Ingredients Equipment Method Notes

Ingredients
  

  • 3 pounds sweet potatoes, peeled and thinly sliced about 1/8 inch thick
  • 2 tablespoons olive oil
  • 1 teaspoon salt
  • 1/2 teaspoon black pepper
  • 4 tablespoons butter
  • 1 medium yellow onion, finely chopped
  • 2 cloves garlic, minced
  • 1/4 cup all-purpose flour
  • 3 cups milk whole or 2%
  • 1/2 teaspoon ground nutmeg
  • 1/4 teaspoon cayenne pepper optional
  • 1 teaspoon salt
  • 1/2 teaspoon black pepper
  • 1 cup shredded Gruyere cheese or Swiss cheese
  • 1/2 cup panko breadcrumbs
  • 2 tablespoons melted butter
  • 1/4 cup grated Parmesan cheese

Equipment

  • 9x13 inch baking dish
  • Large bowl
  • Vegetable peeler
  • Sharp Knife or Mandoline
  • Large saucepan
  • Whisk
  • Small bowl
  • Measuring cups and spoons
  • Oven

Method
 

  1. Preheat your oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish.
  2. In a large bowl, toss the sweet potato slices with olive oil, 1 teaspoon of salt, and 1/2 teaspoon of black pepper. Make sure the slices are evenly coated.
  3. In a large saucepan, melt the butter over medium heat. Add the chopped onion and cook until softened, about 5 minutes. Add the minced garlic and cook for another minute until fragrant.
  4. Sprinkle the flour over the onion and garlic mixture. Cook, stirring constantly, for 1-2 minutes until the flour is incorporated and the mixture is smooth.
  5. Gradually whisk in the milk, making sure to break up any lumps. Continue whisking until the sauce is smooth.
  6. Bring the sauce to a simmer over medium heat, stirring occasionally. Reduce the heat to low and simmer for 5-7 minutes, or until the sauce has thickened slightly. Stir in the nutmeg, cayenne pepper (if using), 1 teaspoon of salt, and 1/2 teaspoon of black pepper.
  7. Remove the saucepan from the heat and stir in 3/4 cup of the shredded Gruyere cheese until melted and smooth. Reserve the remaining 1/4 cup for topping.
  8. Spread a thin layer of the creamy sauce on the bottom of the prepared baking dish. Arrange a layer of sweet potato slices over the sauce, slightly overlapping them.
  9. Pour another layer of the creamy sauce over the sweet potatoes. Repeat layering the sweet potatoes and sauce until all the sweet potatoes are used, ending with a layer of sauce on top.
  10. Sprinkle the remaining 1/4 cup of Gruyere cheese over the top of the casserole.
  11. In a small bowl, combine the panko breadcrumbs, melted butter, and grated Parmesan cheese. Toss until well combined.
  12. Sprinkle the panko mixture evenly over the top of the casserole.
  13. Bake in the preheated oven for 45-55 minutes, or until the sweet potatoes are tender and the topping is golden brown and crispy.
  14. Remove the casserole from the oven and let it rest for 10-15 minutes before serving.

Notes

Even slicing is key to ensure the sweet potatoes cook evenly. Use a mandoline or a very sharp knife. Don't overcook the sauce; simmer until it's just thick enough to coat the back of a spoon. Gruyere is recommended, but Swiss, Fontina, or sharp cheddar can also be used. Add crispy bacon crumbles to the topping or layered throughout the casserole. For a vegetarian version, use vegetable broth instead of milk. Leftover casserole can be stored in the refrigerator for up to 3 days and reheated in the oven at 350°F (175°C) for 20-25 minutes or in the microwave.