Peel and mash the banana.
Add eggs and sugar to a bowl and mix.
Add the mashed banana, milk, and melted butter, and mix.
Sift in flour, baking powder, and cocoa powder, and mix evenly.
Add chocolate chips and mix thoroughly into the batter.
Pour the batter into a mold and bake in a preheated oven at 170°C for 35 minutes.
Cool the finished cake and slice.