Mash the bananas with a fork and stir together with the sugar and vanilla sugar until creamy.
Stir in eggs and oil. Then add creme fraiche.
Mix the flour, baking cocoa, baking soda and salt in a small bowl and stir into the moist mixture.
Roughly chop the chocolate and nuts and mix in as well.
Grease a flat form (22x22cm) and pour in the dough. Or a large loaf pan.
Bake at 180 degrees top / bottom heat on the middle rack for about 45 minutes (loaf pan 60 minutes). Make a stick test shortly before the end, if necessary extend the baking time.
Let cool in the mold, carefully remove and let cool down completely on a wire rack. Also freezes well.