Combine flour, oats, cinnamon, baking soda, and salt and stir to mix.
In a separate bowl, beat banana. Add coconut oil, sugar, vanilla, and egg and beat with hand mixer. Pour wet ingredients into dry ingredients and mix with hand mixer until just combined. Don’t over mix!
Prepare a baking sheet by either lining it with parchment paper or spraying with cooking spray.
Roll dough into 1-inch balls. Place rolled balls onto baking sheet with at least an inch of space between them. Flatten to about ½ inch thick with fingers.
Bake for 12 – 13 minutes until edges are starting to brown lightly. Let cool on baking sheet for 10 – 15 minutes.
Cool fully on a cooling rack before storing in an airtight container. Cookies will keep for about three days.