Finely chop the cranberries. Cream butter, icing sugar, vanillin sugar and salt with the whisk of the hand mixer. Stir in egg yolk. Add flour, cinnamon and milk. Finally stir in half of the buckwheat flakes and the cranberries.
Form the dough into small balls with floured hands. Mix remaining flakes and cranberries, roll balls in it. Place on 2 baking trays lined with baking paper. Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 12-15 minutes.
Allow to cool on cake racks.