Halve the cherries and pistachio kernels. Cream softened butter, sugar and vanilla sugar with the whisk of the hand mixer. Add egg and sour cream and stir in. Mix flour and baking powder. Add and work into a smooth dough with the dough hooks of the hand mixer. Roll out the dough on a well floured work surface and cut out 35 flowers (5.5 cm Ø).
Put the flowers on 2 baking trays lined with baking paper. Whisk milk and egg yolk and brush the flowers with it. Decorate with cherries and pistachios. Bake one after the other in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: stage 2) for 10-12 minutes until golden brown. Remove the flowers from the oven and let them cool on a cake rack