In a medium bowl, mx together oats, flour, baking soda, cinnamon and salt until fully combined.
In a large mixing bowl, mash the banana. Add the butter, egg, brown sugar and vanilla and beat until very well combined.
Add the dry ingredients to the wet ingredients and mix until fully combined. Stir in the chocolate chips.
Refrigerate dough for at least 1 hour.
Towards the end of the dough chilling process, preheat the oven to 350 degrees and prepare a baking pan with parchment paper or a silicon sheet.
Bake for 11-14 minutes.