Preheat oven to 350 degrees, line muffin tin with wrappers, set aside.
In a bowl, whisk together the flour, sugar, baking powder, baking soda and salt.
In another bowl, combine the bananas, oil, vanilla and egg.
Add the wet mixture to the dry and mix until JUST combined (don't overmix it)
Scoop batter into 12 cupcake liners. I used a large cookie scoop to do this, but aim for 2/3 full.
Bake for 18 minutes, or until they spring back when you touch them lightly.
Cool in the pan for a few minutes, then set on a wire cooling rack until completely cool. Frost.