First, heat the milk, sprinkle in the rice and cook over low heat for about 15 minutes. Allow the rice pudding to cool completely.
Separate the eggs and beat the egg whites until stiff. Beat yolks, butter, sugar, vanilla sugar, lemon zest until creamy.
Stir in cold rice pudding, carefully fold in the snow.
Peel apple and cut into thin slices.
Butter a baking dish and sprinkle with breadcrumbs.
Pour half of the mixture into the dish, place apple slices on top, sprinkle with cinnamon and cover with the remaining mixture.
Bake the casserole at 180 °C top/bottom heat for about 1 hour.