- Preheat oven to 350 degrees F (175 degrees C).
- Place potatoes, garlic, and salt into a large pot, fill with enough water to cover, and bring to a boil. Reduce heat to medium, and simmer the potatoes until tender but not mushy, 8 to 10 minutes. With a slotted spoon, transfer about half the potatoes to a 9×13-inch baking dish.
- Pour half of the cream over the potatoes, season with black pepper and nutmeg, and sprinkle half of the Gruyere cheese onto the mixture. Top with the remaining potatoes; sprinkle again with black pepper and nutmeg. Pour on the remaining cream, and sprinkle with remaining Gruyere cheese.
- Bake in the preheated oven until the cheese topping is crisp and brown on top, about 1 hour.