Chef Michael White has perfected potato gratin using two types of cheese, thyme, and nutmeg. Ooey-gooey, bubbly, and decadent, it's way more than just a side dish.
Preheat oven to 375°F. Butter a 9x13-inch casserole dish. Heat the oil in a saucepan; add the onions, garlic, and thyme, and cook over medium heat until the onions are translucent. Add the cream and nutmeg, bring to a boil, and simmer for 3 to 4 minutes. Season with salt and pepper, and whisk to combine. Set aside to cool slightly.
Combine the potatoes in a large bowl with the cream mixture, and stir to coat. Stir together the cheeses in a separate bowl. Layer the potato in the casserole dish, sprinkle with the cheese, and repeat, alternating layers. Pour remaining cream over the gratin, and finish the top layer with cheese. Cover with foil, and bake for about 45 minutes. Remove foil, and continue to bake for a further 30 minutes, until golden. Let cool slightly to allow the gratin to set before serving.