Separate the egg, cover and chill the egg white. Knead flour, butter in flakes, egg yolk, icing sugar and vanillin sugar first with the dough hooks of the hand mixer, then with your hands to a smooth dough.
Wrap in foil and chill for about 30 minutes.
Finely mix the pistachios in a universal chopper. Mix the pistachios and 50 g sugar. Halve the dough. Roll out halves one after the other on a floured work surface in a rectangular shape (approx. 20 x 30 cm).
Spread about half of the pistachio-sugar mixture on each. Roll up the dough, starting from the long side. Wrap both rolls in foil and let them rest in the refrigerator for 2-3 hours.
Unpack the dough rolls, brush them thinly with egg white and roll them in the remaining sugar. Cut rolls into approx. 0.5 cm thick slices and spread them on 3 baking trays lined with baking paper. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see
manufacturer) Bake for 10-12 minutes. Remove and let cool on a cake rack.