Sweet Potato Gratin Cheese (Print Version)
Sweet potatoes, Gruyère, herbs, and spices, baked in a creamy, cheesy, golden dish.
# Ingredients:
→ Dairy and Cheese
01 -
3 tablespoons unsalted butter, softened and divided
02 -
1 cup heavy cream
03 -
3/4 cup whole milk
04 -
3/4 cup grated Parmesan cheese, divided (approximately 2 ounces)
05 -
2 2/3 cups shredded Gruyère cheese, divided (approximately 8.5 ounces)
→ Vegetables
06 -
2 pounds sweet potatoes, peeled and sliced 1/8-inch thick
→ Herbs and Seasonings
07 -
4 teaspoons chopped garlic
08 -
2 tablespoons fresh thyme leaves, chopped (plus more for finishing)
09 -
1 tablespoon fresh sage leaves, chopped
10 -
Kosher salt
11 -
1/4 teaspoon ground cinnamon
12 -
1/4 teaspoon ground nutmeg
13 -
Freshly ground black pepper
→ Other
14 -
2 large eggs
# Steps:
01 -
Preheat the oven to 375°F (190°C). Generously butter a 2-quart casserole or gratin dish using 1 tablespoon of the unsalted butter.
02 -
In a small saucepan over medium heat, melt the remaining 2 tablespoons unsalted butter. Once the foaming subsides, add chopped garlic and cook until fragrant, about 30 seconds. Add the chopped thyme, sage, and approximately 1/2 teaspoon kosher salt; cook for another 30 seconds. Stir in the heavy cream, whole milk, ground cinnamon, and nutmeg. Bring to a gentle simmer, avoiding a full boil, and cook while stirring occasionally until slightly thickened, about 5 minutes. Remove from heat.
03 -
In a medium bowl, beat the eggs. Gradually whisk about 1 cup of the hot cream mixture into the eggs to temper. Return the egg-cream mixture to the saucepan and whisk until thoroughly combined. Stir in 1/2 cup of the Parmesan cheese and season with freshly ground black pepper.
04 -
Arrange a layer of sweet potato slices, overlapping slightly, in the prepared dish. Lightly season with kosher salt. Sprinkle with approximately 2/3 cup shredded Gruyère cheese and ladle over about 2/3 cup of the cream-egg mixture. Repeat the process of layering potatoes, seasoning, cheese, and cream mixture for a total of about four layers, finishing with the cream mixture.
05 -
Sprinkle the remaining 1/4 cup Parmesan cheese evenly over the top layer. Butter a piece of foil and cover the dish tightly with the buttered side down.
06 -
Bake covered for 30 minutes. Remove the foil and continue baking uncovered for about 30 minutes more, until the gratin is bubbling at the edges, golden brown, and the potatoes are tender when pierced.
07 -
Remove from the oven and allow to stand briefly. Finish with additional fresh thyme leaves and serve warm.
# Notes:
01 -
For neat layers, use a mandoline slicer for uniformly thin potato slices. The gratin can be assembled several hours ahead and baked just before serving.