- 2 cups heavy cream
- 1½ tablespoons chopped fresh thyme
- 1¼ teaspoons kosher salt
- ½ teaspoon black pepper
- ¼ teaspoon cayenne pepper
- 3 pounds sweet potatoes, peeled and cut into ¼-inch slices
- 4 ounces Gruyère cheese, shredded (about 1 cup)
- Preheat oven to 350°F. Whisk together the cream, thyme, salt, black pepper, and cayenne.
- Arrange a fourth of the sweet potatoes, with slices slightly overlapping, in a lightly greased 11-by-7-inch baking dish; drizzle with ½ cup of the cream mixture. Repeat the layers 3 more times.
- Cover with aluminum foil and bake 30 minutes. Remove the foil; sprinkle with the cheese and bake, uncovered, until the sweet potatoes are tender and the top is golden brown, about 45 minutes. Let stand 15 minutes before serving.