Beat egg whites into snow. Mix egg yolks, margarine, powdered sugar and vanilla sugar until frothy. Wash, peel and grate the apples. Grate the chocolate as well. Add to the egg yolk and sugar mixture together with the hazelnuts and mix. Add flour and baking powder and finally fold in the snow. Pour into a ring cake pan and bake at 180 ° C (hot air) for about 1 hour. Then let it cool down.