Peel the potatoes, cut into thin slices, wash and pat dry. Peel the apples and cut into thin slices. Layer alternately potatoes and apples in a greased dish. Season the potatoes with salt and pepper. Pour the cream over it. Cover the tin with aluminum foil and bake in the oven for 50 minutes at 200 °. Just before the end of the 50 minutes, remove the aluminum foil so that the gratin browns.