Mix the butter with the eggs and sugar until frothy. Mix flour with baking powder and vanilla sugar and add to the already mixed. Mix again and then add the 4 tablespoons of milk.
Depending on your preference, you can add cocoa powder and / or chocolate chips to the dough. Mix well again and then pour into the muffin tins.
Then bake the finished tray for 15-20 minutes at 200 °.