In a small bowl, mix together the ground flaxseed and water. Set aside.
Preheat oven to 350 degrees. Spray a large baking sheet with cooking spray.
Combine butter, brown sugar, and maple syrup in a mixing bowl, and beat with an electric mixer. Add in banana, vanilla, oil, and the flax egg, and beat again until smooth.
Mix in the flours, cinnamon, salt, and baking powder, and beat just until combined. Stir in the chocolate chips and oats.
Drop spoonfuls of batter onto the baking sheet a few inches apart from each other to form 24 cookies. Bake for 12 minutes, or until the edges are lightly browned. Allow to cool on a baking rack.