- 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 Tbsp lightly packed fresh thyme
- Coarse salt and freshly ground pepper
- 1/8 tsp nutmeg
- 6 oz Gruyere, coarsely grated (2 ¼ cups)
- 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.
- Transfer potatoes and garlic to a large pot with cream, milk, thyme, 1 TBSP salt, ½ tsp pepper, and nutmeg. Bring to a boil over high.
- Reduce heat to medium and simmer 1 minute. Let cool slightly, about 10 minutes.
- 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.
- Bake until potatoes are tender, 35-45 minutes. Remove foil, turn oven to broil and broil until potatoes are bubbly and browned in places, 3-5 minutes.
- Let cool 15 minutes before serving.
This dish can largely be assembled ahead; leave off the last portion of cheese, cover the dish with plastic wrap (pressing it directly onto the surface to prevent a skin from forming), and refrigerate it for up to one day. Remove it 30 minutes before baking, sprinkle with the remaining cheese and bake as instructed.