Here's one of mine. It's a little time consuming but worth it. Don't skimp on the Gruyere tho -- it makes the dish.
1 lb (450 g) medium potatoes, peeled and sliced into thin rounds
salt and freshly ground black pepper
pinch nutmeg, freshly grated is best
2 3/4 cups (21 fl oz) 600 ml milk, warmed, can be low fat
1 egg, beaten
1/2 stick (2 oz) 50 g butter
2 oz (50 g) or more to taste Gruyere cheese, grated
1 garlic clove
1 small onion
1. Heat the oven to 350°F (177°C)
2. Rub a shallow ovenproof dish well with garlic and butter it. Layer potatoes and onions, dotting each layer with butter, salt, pepper, nutmeg and cheese. Leave about 1/2 cup cheese aside.
3. Beat the egg and strain into the warm milk.
4. Pour mixture over potatoes, shaking to make sure it is evenly dispersed.
5. Sprinkle the remaining cheese on top and dot with butter.
6. Bake in a preheated oven for 30 - 40 minutes or until the potatoes are cooked through and the dish is golden and crispy on top. I usually cook it covered for about 35 minutes, then take the cover off.