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Sweet Potato Au Gratin

Cheesy Sweet Potato Au Gratin

This sweet potato au gratin features thinly sliced potatoes baked in a rich and creamy Gruyere cheese sauce with a hint of garlic and thyme. It's a comforting, savory-sweet side dish that’s perfect for any occasion.
Prep Time 15 minutes
Cook Time 45 minutes
Total Time 1 hour
Course Side Dish
Cuisine American
Servings 8
Calories 380 kcal

Ingredients
  

  • 3 pounds sweet potatoes (peeled and thinly sliced 1/8 inch)
  • 1 ½ cups heavy cream
  • 1 ½ cups shredded Gruyere cheese (divided)
  • ½ cup grated Parmesan cheese
  • 4 tablespoons butter (divided)
  • 2 cloves garlic (minced)
  • 1 teaspoon fresh thyme leaves
  • salt and black pepper to taste

Instructions
 

  • Preheat oven: Set your oven to 400°F (200°C). Grease a 9x13 inch baking dish with 1 tbsp of butter.
  • Make cream Ssuce: Melt 3 tbsp of butter in a saucepan over medium heat. Cook 2 minced garlic cloves for 1 minute. Stir in 1 ½ cups of heavy cream and simmer gently.
  • Add cheese: Remove the pan from the heat. Stir in 1 cup of Gruyere, ½ cup of Parmesan, and 1 tsp of thyme until smooth. Season with salt and pepper.
  • Layer potatoes: Arrange half of the sweet potato slices in the prepared dish. Pour half of the creamy sauce over the top.
  • Add final layer: Layer the remaining sweet potato slices on top. Pour the rest of the sauce over everything. Sprinkle with the remaining ½ cup of Gruyere.
  • Bake and serve: Bake for 45-55 minutes, until the top is golden and the potatoes are tender. Let it rest for 10 minutes before serving. ENJOY!

Notes

  • A mandoline slicer is highly recommended for even slices.
  • Grating your own cheese will give you the creamiest results.
  • Let the gratin rest before serving so the sauce can set.
  • Feel free to add a pinch of nutmeg for extra warmth.
  • Store any leftovers in the fridge for up to 4 days.