Preheat oven to gas mark 4
Line a 2lb non stick loaf tin with parchment/greaseproof paper.
Combine the flour, baking powder, bicarbonate of soda, salt and cocoa.
In a separate bowl cream the butter and sugar until light and fluffy using a free stand mixer or hand mixer.
Add the eggs, bananas, milk, vanilla essence and cinnamon to the butter mixture and mix for 5 minutes.
Fold in the flour and chocolate chips.
Put the mixture into the loaf tin and bake for one hour.
Check at 50 minutes by sticking a metal skewer into the middle of the cake. If it comes out clean, the cake is done. If there is just a little mixture on the skewer, that is fine as it is better slightly under, then overcooked and it will continue to bake in the residual heat.