Preheat your oven to 180C / 350F / Gas mark 4 and either line or lightly grease a 2lb loaf tin, and place to one side.
In a small mixing bowl, combine the flour, cocoa powder, baking soda and salt then place it aside.
In a large mixing bowl, add in the mashed bananas and mix them with the melted butter and oil.
Then add the sugar, egg and vanilla extract and mix until smooth.
Pour in the dry ingredients and with a gentle hand fold them in together.
Fold in 2/3rds of the chocolate chips and transfer the batter into your prepared loaf tin.
Place the peanut butter into a microwavable dish and microwave for 15 seconds. You don't want to heat it up, just make it a little runny. Once that is done mix in the maple syrup then swirl it into the batter of your banana bread.
Sprinkle the remaining chocolate chips on top and place it into your warm oven.
I have a very slow oven so it took an hour to bake through but check on your loaf at the 50-minute mark. An inserted pick should come out clean, or with only a few crumbs on it.
Once baked through, leave your loaf to cool for 15 minutes in the tin. Then gently turn it out onto a wire rack to fully cool down.
This loaf can be kept in a cool environment in an airtight tin for 5 days. This loaf also freezes well, either freeze it as a whole or cut it up into slices and freeze the individual slices.