Put flour, 125 g sugar, vanilla pulp, salt, cocoa, egg and butter in flakes in a mixing bowl. Knead first with the dough hooks of the hand mixer, then with your hands to a smooth dough. Wrap in foil and chill for about 45 minutes
Halve the walnut kernels lengthwise. Roll out the dough on a floured work surface to a thickness of about 3 mm. Cut out circles (4 cm Ø), knead the remaining dough again and cut out a total of 78 circles. Place on 3 baking trays lined with baking paper
Beat the egg white with the whisk of the hand mixer until stiff, add lemon juice, pour in 200 g sugar. Keep beating until the beaten egg whites are shiny white. Pour the tuffs in portions into a piping bag with a perforated spout and spray them onto the cut-out dough circles (leave a rim of approx. 2 mm, as the egg white will rise during baking). Place a piece of walnut in the middle of each circle
Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 12-15 minutes, one after the other. Remove from the oven, carefully place on a cake rack, allow to cool and pack in tins
waiting time approx. 1 1/4 hours