Knead the butter in pieces, sugar, flour, vanillin sugar and egg first with the dough hooks of the hand mixer, then with your hands to a smooth dough. Wrap dough in foil and chill for about 30 minutes.
Roll out to a thickness of about 3 mm on a floured work surface. Cut out approx. 60 circles (approx. 6 cm Ø). Put the biscuits on about 2 baking trays lined with baking paper. Bake one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 8-10 minutes. Let them cool down.
Meanwhile melt the nougat over a warm water bath. Spread half of the biscuits with some nougat and put a second biscuit on top as a lid.
Melt the couverture over a warm water bath. Put into a disposable piping bag and cut off a small tip. Spray the couverture in strips onto the cookies and allow to dry.