Preheat oven to 350 degrees.

In a medium bowl, combine banana, peanut butter, vegetable oil, flax egg and vanilla. Mix together well until mostly smooth.

In another bowl, stir together oats, flour, baking powder, salt and brown sugar.

Add dry ingredients to wet ingredients, and stir with a wooden spoon until combined well. Add chocolate chips and stir until evenly incorporated.

Place spoonfuls of batter onto a large, greased baking sheet. Form 18 cookies.

Cook for about 12 minutes, or until lightly browned on the bottom. Allow to slightly cool on a cooling rack before enjoying (if you can wait a few minutes!).