A rich, cheesy, sweet potato gratin with sage and rosemary is sweet, savory & perfect for Thanksgiving.
- 3 tbsp butter, softened
- ⅓ cup grated Parmesan
- 2 cups heavy cream
- 3 tbsp fresh sage, chopped
- 1 tbsp fresh rosemary, finely chopped
- 1 tbsp fresh thyme leaves
- 3–4 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
- fresh ground black pepper
- 1.5 cups grated Gruyère cheese
- Heat oven to 400 degrees.
- Butter a 10.5″ X 7.5″ baking pan or gratin dish. I used this one from Staub.
- Butter a piece of foil large enough to cover your pan. Sprinkle Parmesan all over the bottom of your pan.
- 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.
- 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.
- Using a mandoline or sharp knife, slice the potatoes into 1/8-inch-thick rounds.
- Place a layer of potatoes in the pan, slightly overlapping as you go.
- 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.
- 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.
- 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.
- 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