In a medium sized bowl, mix together the remaining ingredients–mashed bananas, coconut oil, vanilla, and egg, stirring to combine. Add the wet mixture to the dry and stir until just combined. Don’t overmix. Divide the batter among the 12 cupcakes wrappers, about ⅔ of the way full (I used a large cookie scoop). Bake for 17-19 minutes, until a toothpick inserted comes out mostly clean. Cool on rack for 5 minutes, then remove from pan and place directly on rack to cool completely.