Preheat the oven to 375F/170C Prepare a muffin pan with twelve muffin cases (or if making a loaf, grease the pan)
Melt the butter, add the bananas and mash well with a potato masher. Add the rest of the ingredients (besides the chocolate chips) to the bowl and mix until just incorporated. Fold in the chocolate chips until evenly distributed into the batter.
Using an ice cream scoop add the batter into muffin cases and top with the banana chips. Bake for about 20 minutes or until a cake tester comes out clean.
Cool in the pan for 10 minutes, then remove and cool on a wire rack.
Be sure to use very ripe bananas. Black bananas are best.
The riper the banana the more flavor and the easier it mashes. If you only have yellow bananas add them to the butter to be melted. The heat will help them mash easier.