Beat the butter, icing sugar and vanilla sugar until creamy with the whisk of the hand mixer. Stir in orange zest, eggs and milk one after the other. Mix flour and cocoa, stir in briefly. Pour the dough into a piping bag with a large star-shaped spout. Line 3 baking trays with baking paper. Spray approx. 70 flat tuffs onto the baking paper, pull the spout away to the side
Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 6-8 minutes, allow to cool. Fill chocolate cream into a piping bag. Spray cream on the underside of 35 biscuits. Place the remaining biscuits on top and press down slightly. Packed cool and airtight, the shortbreads will keep for about 2 weeks.
Waiting time approx. 1 hour