Preheat Oven: Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish with butter.
Prepare Cream Mixture: In a saucepan over medium heat, combine heavy cream, milk, garlic, salt, pepper, and nutmeg. Heat until warm but not boiling.
Layer Potatoes: Arrange half of the potato slices in the prepared baking dish. Pour half of the cream mixture over the potatoes and sprinkle with half of the cheese.
Second Layer: Layer the remaining potatoes, pour the rest of the cream, and top with remaining cheese.
Bake: Cover with aluminum foil and bake for 35–40 minutes. Remove foil and bake an additional 20–25 minutes, until the top is golden brown and the potatoes are tender when pierced with a fork.
Rest & Serve: Let the gratin rest for 5–10 minutes before serving to allow it to set slightly.
Serving and Storage Tips
