Mix the whites together with a whisk, but do not beat them.
Add cocoa powder and powdered sugar, mix well.
At last add coconut flakes and mix dough untill incorporated.
Roll the dough into balls the size of a large walnut and place on a baking sheet lined with baking paper. The distance between the balls is approximately 3 cm.
Bake for 15 minutes or a little longer: the cookies should burn.