1 clove garlic, lightly smashed and peeled Unsalted butter, room temperature, for pan 4 pounds Yukon Gold potatoes (8 medium) 2 cups heavy cream 2 cups whole milk 1 tablespoon lightly packed fresh thyme leaves Coarse salt and freshly ground pepper 1/8 teaspoon freshly grated nutmeg 6 ounces Gruyere, coarsely grated (2 1/4 cups)

1. Preheat oven to 375 degrees. Rub the bottom and sides of a 3-quart baking dish with garlic; reserve garlic. Brush pan generously with butter. Peel potatoes, then cut into 1/8-inch-thick rounds. 2. Transfer potatoes and garlic to a large pot with cream, milk, thyme, 1 tablespoon salt, 1/2 teaspoon pepper, and nutmeg. Bring to a boil over high. Reduce heat to medium and simmer 1 minute. Let cool slightly, about 10 minutes. 3. Spoon one-third of potato mixture into prepared dish. Sprinkle with one-third of cheese. Repeat layering twice more. Loosely cover dish with parchment-lined foil. 4. Bake until potatoes are tender when pierced with the tip of a knife, 35 to 40 minutes. Remove foil; turn oven to broil. Broil until potatoes are bubbly and browned in places, 3 to 5 minutes. Let cool 15 minutes before serving.