Preheat the oven to 180 degrees C.
Line a 2lb loaf tin with greaseproof paper.
Add the bananas, oil, milk and sugar to a food processor and blitz for a few minutes until smooth.
Pour the mixture into a large bowl and add the remaining ingredients, flour first and chocolate last, while stirring to combine everything together.
Add the mixture to the lined baking tray, give it a shake to ensure the contents are even and smooth over with the back of a spoon if necessary.
Place in the oven and bake for about 45 minutes. If it starts to brown too much on top, place a piece of foil over it to prevent it from burning.
Test the loaf is cooked all the way through by inserting a skewer through the middle and checking it comes out clean. If not, return it to the oven for another 5-10 minutes.
Remove the loaf from the oven once cooked, leave it to cool for 5 minutes in the loaf tin, then remove it by carefully lifting it out using the greaseproof paper. Place it on a cooling rack and leave to cool for a further 15+ minutes.
It can be sliced and enjoyed immediately or left to cool completely before storing in a lidded, airtight container. If it is not cooled completely, the moisture will create condensation and it will become soggy in the container.