Try this one. And use Swiss Cheese, if you can't find Gruyère.
This is the best Potato Gratin I have ever eaten.
CHEESY POTATO GRATIN
1 clove garlic, peeled and halved
3 cups milk
3 pounds (about 5) Idaho russet potatoes peeled & very thinly sliced
2 large eggs, lightly beaten
1 1/2 teaspoons sea salt
freshly ground black pepper to taste
1 cup (3 ounces) grated Gruyère cheese
1/2 cup crème fraîche or heavy cream
Preheat the oven to 400 degrees F.
Rub the inside of an oval porcelain gratin dish (about 14 x 9 x 2 inches) with the garlic. Arrange the potatoes in an even layer in the dish.
Mix the milk, eggs and salt and pour over the potatoes. Sprinkle generously with pepper.
Bake, occasionally cutting the crust that forms on top and gently folding it into the potatoes, until the gratin is golden, about 55 minutes.
Remove the gratin dish from the oven, sprinkle with the grated cheese, then dab the gratin with crème fraîche. Return the dish to the oven and bake until the top is very crisp and golden, about 15 minutes.
Wine is the food that completes the meal.