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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.

Prep Time
30 mins
Cook Time
30 mins
Total Time
1 hr 15 mins
Servings: 8 servings
Calories: 372 kcal
Course: Side Dish
Cuisine: American

Ingredients

  • 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

Instructions

    Cup of Yum
  1. Preheat the oven to 375 degrees.
  2. 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. Lay Potatoes in Baking Dish: Spray a 13x9-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
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. Serve sweet potatoes au gratin immediately with a sprinkle of finely chopped fresh rosemary and thyme.

Notes

  • Storage: Keep leftovers in an airtight container in the refrigerator for up to 4 to 5 days.
  • Potatoes: Cut them equally thin so they cook at the same rate.
  • Topping: Don't add the breadcrumbs right away or they'll burn.
  • Cheese: You can sub a dairy-free cheese if necessary, or choose a different variety.

Nutrition Information

Calories 372kcal (19%) Carbohydrates 44g (15%) Protein 14g (28%) Fat 16g (25%) Saturated Fat 9g (45%) Polyunsaturated Fat 1g Monounsaturated Fat 4g Trans Fat 0.2g Cholesterol 46mg (15%) Sodium 903mg (38%) Potassium 643mg (18%) Fiber 6g (24%) Sugar 11g (22%) Vitamin A 24710IU (494%) Vitamin C 5mg (6%) Calcium 442mg (44%) Iron 2mg (11%)

Nutrition Facts

Serving: 8servings

Amount Per Serving

Calories 372

% Daily Value*

Calories 372kcal 19%
Carbohydrates 44g 15%
Protein 14g 28%
Fat 16g 25%
Saturated Fat 9g 45%
Polyunsaturated Fat 1g 6%
Monounsaturated Fat 4g 20%
Trans Fat 0.2g 10%
Cholesterol 46mg 15%
Sodium 903mg 38%
Potassium 643mg 14%
Fiber 6g 24%
Sugar 11g 22%
Vitamin A 24710IU 494%
Vitamin C 5mg 6%
Calcium 442mg 44%
Iron 2mg 11%

* Percent Daily Values are based on a 2,000 calorie diet.