Quickly mix flour, sugar, vanilla sugar, egg, cocoa powder and 125 g butter in flakes with the dough hooks of the hand mixer to a smooth dough. Wrap in foil and chill for approx. 30 minutes
Roll out the dough on a floured work surface and cut out about 40 squares (approx. 5 x 5 cm). Knead the remaining dough, roll out again and cut out. Place on 2 baking trays lined with baking paper. Bake one after the other in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for 12-15 minutes. Place the cookies on a cake rack and let them cool down
Whisk 75 g butter with the whisk of the hand mixer until whitecreamy, gradually add icing sugar. Stir in cream cheese with a whisk. Chill the cream for about 20 minutes. Spread 20 squares on the underside with hazelnut cream. Spread the remaining squares with the butter cream. Place 1 cookie on each square with the hazelnut cream facing down and arrange
waiting time approx. 2 hours