Sweet Potato and Gruyère Gratin

  • Author: Jenny
  • Prep Time: 10 min
  • Cook Time: 70 min
  • Total Time: 1 hour 20 minutes
  • Yield: 6 1x
  • Method: Oven


A rich, cheesy, sweet potato gratin with sage and rosemary is sweet, savory & perfect for Thanksgiving.



  • 3 tbsp butter, softened
  • cup grated Parmesan
  • 2 cups heavy cream 
  • 3 tbsp fresh sage, chopped
  • 1 tbsp fresh rosemary, finely chopped
  • 1 tbsp fresh thyme leaves
  • 34 cloves
  • 4 large cloves of garlic grated 
  • ¼ tsp grated nutmeg
  • 3 eggs, lightly beaten
  • 2 large sweet potatoes (about 4 large or 5 medium), peeled
  • salt
  • fresh ground black pepper
  • 1.5 cups grated Gruyère cheese


  1. Heat oven to 400 degrees.
  2. Butter a 10.5″ X 7.5″ baking pan or gratin dish. I used this one from Staub.
  3. Butter a piece of foil large enough to cover your pan. Sprinkle Parmesan all over the bottom of your pan.
  4. In a medium pot, bring cream, sage, rosemary, cloves, thyme, garlic, nutmeg and a pinch of salt to a simmer. Simmer until reduced a little, about 10 minutes.
  5. In a large bowl, whisk the eggs just enough to break them up. Slowly pour the hot cream into the eggs, keep whisking while pouring. Mix well. Set aside.
  6. Using a mandoline or sharp knife, slice the potatoes into 1/8-inch-thick rounds.
  7. Place a layer of potatoes in the pan, slightly overlapping as you go.
  8. Sprinkle a small pinch of salt and fresh ground pepper over potatoes., then pour 1/3 of the egg mixture all over. Top with 1/2 cup Gruyère.
  9. Repeat with another layer of potatoes, a small pinch of salt and fresh ground pepper and 1/3 egg mixture. Top again with 1/2 cup Gruyère.
  10. Top with remaining potatoes, a small pinch of salt and fresh ground pepper, and remaining egg mixture . Don’t add any cheese. Cover with foil and bake until potatoes are tender, about 40 minutes.
  11. Remove foil, sprinkle top with remaining 1/2 cup Gruyère and bake until browned and bubbling, 25 to 30 minutes. Let cool a little then serve.

Keywords: Sweet Potato Au Gratin, Sweet Potato Casserole, Thanksgiving Casserole, Holiday Menu, Holiday Casserole, Au Gratin, Gruyere Au Gratin

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