Preheat oven to 350.
Place butter and both sugars in bowl of stand mixer, and beat with paddle attachment on speed 2 until smooth.
Add egg, mixing until fully incorporated on speed 2.
Add banana, vanilla, cinnamon, baking powder, baking soda, and salt, mixing well on speed 2.
Use a spatula to down the sides and bottom of the bowl, and mix again.
Add flour, mixing on low; scrape sides and bottom with spatula and mix on low until fully blended.
Scoop approximately 1-1/2 tablespoons batter, spaced evenly on a parchment-paper lined baking sheet.
Bake for 15-20 minutes, or until cakes spring back when touched.
Allow to cool for 2 minutes on baking sheet.
Transfer to baking rack to cool completely.