The key to achieving the perfect Gratin Dauphinois lies in mastering the technique of layering and baking. Start by thinly slicing your potatoes – a mandoline slicer works wonders here, ensuring uniform slices that cook evenly. Next, layer the potato slices in a buttered baking dish, seasoning each layer with a sprinkle of salt, pepper, and grated nutmeg. Pour the cream and milk mixture over the potatoes, ensuring that each slice is coated in the creamy goodness.