Put the butter, sugar, vanilla sugar and eggs in a bowl and beat until frothy. Add the oatmeal and stir in well. Mix the flour with baking powder and stir in small portions. Add the milk and stir everything well. If necessary, add more milk (the dough must not be too firm, but also not runny).
Use a tablespoon to place small heaps of dough on a baking sheet lined with baking paper and bake for 11-13 minutes at 180 degrees on the bottom rack.
Don`t let the cookies turn brown! After baking, let cool on a wire rack.
Tip: I always put the biscuits in a Tupperware container after they have cooled down and seal it. The cookies taste even better then.