Combine oats, flour, baking powder, cinnamon and salt in medium bowl.
Mix butter, sugar, banana and vanilla in separate bowl. Add egg and mix well. Add dry ingredients to wet ingredients until just incorporated. Mix in chocolate chips. Cover and refrigerate 30 minutes.
Preheat oven to 375°F.
Drop spoonfuls of cookie dough onto parchment-lined baking sheet and press down to flatten.
Bake 10-12 minutes, or until browned. Let cool 5 minutes on baking sheet before transferring to cooling rack.
