Whisk the eggs, sugar and vanilla sugar white and foaming with electric whisks (about 5-7 minutes). 

Melt the butter and set aside.

Mix flour, mask flour and baking soda.

Mash the bananas with a fork.

Roughly chop the dark chocolate.

Mix the flour mixture in the egg mass with the melted butter. Then stir the mashed bananas into the mixture and finally add the coarsely chopped chocolate.

Divide the dough into 12 muffin molds.

Bake for 17 - 20 minutes v. 200 degrees.