spray muffin tray with olive oil to prevent muffin mix sticking to the sides of the pan
Mash bananas in a large mixing bowel with fork then add vanilla extract. (This is to ensure that all the wet ingredients are kept separate from dry ingredients.)
Melt butter in microwave then mix with egg in a large mixing bowel. Be sure to use beaters as it is more efficient then whisk. (unless you have a fast hand) Now mix all wet ingredients together.
Now mix flour and choc chips together as well as adding cinnamon sugar also.
Combine all ingredients together and mix with blender. (be sure to start on a low speed so flour doesn't go every where)
Now put mix in muffin tray evenly. (try not to put too much mix in one section because self raising flour will make it rise) Put in oven and bake for 20 minutes or until golden and firm on top when lightly touched.
When you take the muffins out, sprinkle cinnamon sugar for that extra effect. Allow muffins to cool on cooling rack for at least 10 minutes then enjoy!