Preheat the oven to 180 degrees top / bottom heat. Grease the baking pan (wreath / Gugelhupf).
Beat eggs, sugar and vanilla sugar until frothy. Add oil and stir in. Peel the bananas, roughly chop them with a fork and mix with the lemon juice. Stir the bananas into the batter. Mix the flour, baking powder and cocoa, sieve and gradually stir into the batter. Stir the salt into the batter.
Fill the dough into the baking pan and bake for about 50 - 60 minutes (stick test!).