I use this recipe all the time with one secret ingredient... Tamarillo when available (I replace half a banana with 3 or 4 Tamarillos which are prepared by scooping out the centres into a bowl including seeds etc mashing them up and add to the wet mixture below
2cups self raising flour
3/4 tsp bicarb soda
1/3 cup brown sugar
1/4 tsp ground cinnamon
pinch salt
4 over ripe bananas( or 3 and half bananas + 4 Tamarilos)