2 1/4 cups heavy cream
2 tablespoons unsalted butter
1 small onion, sliced
2 garlic cloves, minced
1/8 teaspoon ground nutmeg
1 teaspoon sea salt
1/2 teaspoon ground black pepper
3 1/2 pounds sweet potatoes, peeled and cut into 1/8-inch thick rounds
1 tablespoon chopped sage
2 teaspoons chopped thyme
1 cup shredded Gruyere cheese
1 cup shredded sharp cheddar cheese
- Combine the cream, butter, onion, garlic, nutmeg, salt and pepper in a small saucepan. Bring to a simmer over medium heat then immediately remove from the heat and let stand 15 minutes.
- Preheat the oven to 400°F. Lightly butter and 11x7-inch baking dish.
- Arrange 1/2 of the potatoes in the bottom of the prepared baking dish. Sprinkle with 1 1/2 of the sage and 1 teaspoon of the thyme then top with half of the cheeses. Repeat layering with remaining ingredients. Pour the cream mixture through a strainer over the baking dish. Cover with aluminum foil.
- Bake the sweet potatoes 40 minutes. Uncover, return to the oven and continue baking until the potatoes are tender, the liquid has thickened somewhat and the top is browned, about 30 minutes. Let stand at 15 minutes before serving.