Finely chop 150 g walnuts in the universal chopper. Cut butter into pieces. Knead sugar, butter, ground walnuts, flour, cardamom, cinnamon, flavouring, salt, vanillin sugar and egg first with the dough hooks of the hand mixer, then with your hands on a floured work surface to a smooth dough. Wrap dough in foil and chill for approx. 30 minutes. Roll out the dough on a floured work surface to a thickness of approx. 2 mm and cut out circles (50 pieces; 7 cm Ø).
Spread circles on 3 baking trays lined with baking paper. Knead the remaining dough, roll out and cut out. Bake the trays one after the other in a preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) for 8-10 minutes. Let the cookies cool down on a cake rack. Warm the jam slightly and pass through a sieve. Roughly chop the chocolate and melt in a bowl on a bain-marie (do not let it get too hot). Dip 25 walnut halves halfway into lukewarm chocolate and place on a piece of baking paper. Put the walnut halves in a cool place. Sift icing sugar into a bowl. Add egg white and stir until smooth.
Dip 25 walnut halves halfway into lukewarm chocolate and place on a piece of baking paper. Put the walnut halves in a cool place. Sift icing sugar into a bowl. Add egg white and stir until smooth. Brush half of the cookies with icing sugar and let them dry for about 20 minutes. Place one teaspoon of raspberry jam on each of the other half of the cookies and place the icing lid on top. Put a small spot of jam on each icing and place the walnut half on top
1 hour waiting time