Line a baking sheet with parchment paper. Preheat the oven to around 200 ° C top / bottom heat (hot air: around 180 ° C).
Mix the flour with the baking powder in a mixing bowl. Add sugar, vanilla sugar, salt, egg and butter or margarine and work everything with a mixer (dough hook) first briefly on the lowest, then on the highest level to form a dough.
Knead 3/4 of the dough with the brittle. Knead the cocoa under the rest of the dough. To make the dough two-colored, first roll out the light-colored dough on a floured work surface. Spread the dark rolled out dough on it in dots and then roll out everything together 1/2 cm thick.
Cut out cookies with different motifs, sprinkle with the remaining brittle and bake on the middle rack for about 9 minutes. Let the pastries cool on a wire rack, dust with icing sugar if necessary.
Tips: Possibly put the kneading dough in the refrigerator for about 30 minutes. The rolled out dough remnants can be kneaded into marbled cookies.
The cookies can be kept for about 3 weeks in well-closing cans.