Creating the perfect Potato Gratin is straightforward when you follow these steps:

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Prep the Potatoes: Wash and peel the potatoes. Slice them thinly using a mandoline or sharp knife (about 1/8 inch thick).
3. Make the Cream Mixture: In a mixing bowl, combine the heavy cream, minced garlic, salt, black pepper, and nutmeg. Stir until well mixed.
4. Layer the Potatoes: In a greased 9×13-inch baking dish, arrange a layer of potato slices. Pour a small amount of the cream mixture over the potatoes.
5. Add Cheese: Sprinkle a layer of Gruyère cheese over the cream. Repeat the layering process until all potatoes and cream are used, finishing with a layer of cheese on top.
6. Dot with Butter: Cut the unsalted butter into small pieces and dot them over the top layer of cheese.
7. Cover the Dish: Cover the baking dish tightly with aluminum foil to prevent the top from browning too quickly.
8. Bake: Place the dish in the preheated oven and bake for 45 minutes.
9. Uncover and Brown: After 45 minutes, remove the foil and continue baking for an additional 15-20 minutes, or until the top is golden brown and bubbling.
10. Rest: Once baked, remove the gratin from the oven and let it sit for 15 minutes before serving. This allows the layers to set.

These clear and concise steps will guide you in creating an incredible Potato Gratin that will surely delight everyone at your table.