In a bowl, beat the softened butter with white and brown sugar and vanilla sugar until frothy. Stir in the egg whites (no egg whites!). Mix the flour and baking powder and mix alternately with the water into the frothy buttercream.
Cover each M&M with dough and place on a baking sheet lined with baking paper.
Bake for 8-10 minutes. As soon as the bright color of the M & M`s can be seen on the outside, the cookies are ready. They shouldn`t turn brown on the outside.