For the rafaello slices with sour cream, first stir the sour cream until smooth. Add yogurt, vanilla sugar, powdered sugar, coconut flakes and mix well.
Dissolve gelatin in a little hot water and stir well into the mixture. Fold in whipped cream. Spread the cream on a sponge cake base and decorate with coconut flakes.
Chill the rafaello slices with sour cream for at least 3 hours.