Preheat the oven to 350F. Cream together the butter, sugar, and vanilla sugar until light and fluffy.
Add the all-purpose flour, cake flour, and baker's ammonia and mix until just combined.
Remove pieces of dough and roll into small balls of less than 1 inch in diameter. They should be about 2 tsp in size. Bake at 350F for 12-15 minutes until the tops are cracked and the bottoms are very slightly golden. The cookies should still be pale and look slightly dryer than the dough did.
Allow the cookies to cool on the baking sheet before attempting to transfer them, as they will be very delicate until fully cooled.