Whisk eggs and icing sugar for 45 minutes until foam. Dissolve a 1/2 pill of soda in 1/2 Kirsh. Mix with the egg foam and knead the dough for 15 minutes. Drizzle the baking form with Kirsh, place the dough into the form and put in the cold place ( not the fridge!). Oil 2 baking sheets and sprinkle with anise, knead the dough again. Roll out the dough in the layer with a lot of flour, cut shapes. Cool for several hours. Bake biscuits at 140 degrees Celsius for 30 minutes.