Ingredients (8 portions):

•  250 g of puff pastry
•  5 cooking apples
•  80 g  of chopped hazelnuts
•  20g  of butter
•  1 egg for greasing (yolk)
•  2 pieces of vanilla sugar
•  1 spoon of ground cinnamon 
•  3 spoons of sugar

Method:

Roll out a thin sheet of puff pastry. Cut out circles using a pastry cutter. Place the circles onto a baking tray lined with baking paper.
Using a fork gently make small indents in each circle.  Brush egg yolk over the top. Peel and slice the cooking apples into thin slices.
Place 3 slices of apple in the middle of each circle. Sprinkle on the top the sugar, mixed hazelnuts and a small amount of butter.
Fold the pastry around edge of each circle up, to hold the apple in the middle of each cake. Bake these cakes in a preheated oven at 180°C on the hot-air program for about 25 minutes. The pastry will rise and the apple will caramelize.