4 pounds sweet potatoes, peeled and sliced into 1/8 inch rounds
2 cups heavy cream
3 tablespoons butter
3 cloves garlic, minced
1 teaspoon salt
1/2 teaspoon black pepper
1 tablespoon fresh thyme leaves, plus extra for garnish
1 cup shredded parmesan cheese
1/2 cup sharp cheddar cheese
1/4 teaspoon ground nutmeg
Instructions
Start by preheating your oven to 375 degrees Fahrenheit. Generously grease a 9×13 inch baking dish with butter to ensure the potatoes do not stick and to help create those delicious golden edges around the perimeter of the pan.
Peel the sweet potatoes and slice them into uniform rounds about one eighth of an inch thick. Using a mandoline slicer is the best way to get consistent results, which ensures that all the layers cook at the same rate and the dish has a professional look.
Arrange about one third of the sweet potato slices in the bottom of your prepared baking dish, overlapping them slightly. Sprinkle a third of the parmesan and cheddar cheese over the layer. Repeat this process two more times, ending with a layer of cheese on top. Carefully pour the cream sauce evenly over the entire dish, allowing it to seep down between the layers.
Cover the dish tightly with aluminum foil and bake for 40 minutes. Remove the foil and continue baking for another 20 minutes until the potatoes are tender when pierced with a fork and the cheese on top is bubbly and golden brown. Let the dish rest for 10 minutes before serving to allow the sauce to thicken slightly.
