Knead butter in pieces, icing sugar, flour, 1 egg yolk, 1 pinch of salt, cocoa and gingerbread spice first with the dough hooks of the hand mixer, then with floured hands to a smooth dough. Form the dough into a roll (approx. 24 cm long; 5 cm Ø) on a floured work surface, wrap in foil and chill for approx. 30 minutes
Whisk 1 egg yolk, brush the dough roll with it. Sprinkle the pistachios on a work surface and roll the roll in it. Cut off slices (approx. 5 mm thick) and put them on 2 baking trays covered with baking paper. Bake the trays one after the other in a preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: level 2) for approx. 15 minutes, remove from the oven and allow to cool for approx. 30 minutes
Waiting time approx. 1 hour