Preheat oven to 175°C.
In a bowl take eggs, banana, cocoa powder and baking powder.
Using a hand blender, blend it into a smooth batter.
Grease and dust two ramekins with cocoa powder.
Divide the batter between the ramekins and top it with chopped dark chocolate.
Bake in the preheated oven for 15 - 20 minutes or until a tooth pick inserted comes out clean.
Allow it to cool a little before removing the cake from the ramekin.
Cool completely and enjoy!