Mix butter, icing sugar, salt, vanilla pulp and cinnamon to a smooth mixture. Sift the flour over it and crumble it with your fingers. Knead half to a smooth dough, form into 4 flat bricks, wrap in foil and place in the fridge for approx. 30 minutes. Chop 120 g walnuts. Sift cocoa over the second half of the dough, add walnuts and also work into a smooth dough. Form 4 approx. 20 cm long sticks and put them in the freezer.
Roll out the dough sheets on a lightly floured work surface, each 20 x 12 cm. Whisk egg yolk and cream and brush the dough plates with it. Roll up dark dough sticks and put them back in the fridge for at least 30 minutes. Cut the dough rolls into approx. 25 slices each and spread them on 4 baking trays lined with baking paper. Bake one after the other in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 12 minutes, allow to cool. (The biscuits can be kept for weeks if packed like this.) To decorate, cover the biscuits with the remaining walnut halves. Melt the sugar in a frying pan until golden yellow and drizzle gently over the walnuts