Peel potatoes and then cut into thin slices. Place a single layer in a buttered 2 inch deep full hotel pan.
Season with salt, pepper and nutmeg and sprinkle some gruyere cheese. Continue this process until 75% of the cheese has been used.
Heat the half and half to a simmer then whisk the egg yolks in a separate bowl. Now slowly add warm half and half whisking it into egg yolks. Pour this over the potatoes in the pan and top with the remaining cheese then bake in a preheated 350 degree oven for 1 hour.