Place rack in center of oven and preheat to 375 degrees.
Combine the Oats, Flour, Baking Powder, Baking Soda, Cinnamon, & Salt in Medium Bowl and set aside.
In Large Bowl, use an electric mixer to beat the Butter and Sugars until combined, about 1 minute.
Add the Egg and Vanilla Extract and beat until Blended.
Slowly add Flour Mixture, 1 cup at a time, use low speed on mixer to blend.
Next, gently fold in Chocolate Chips and Banana with a wooden spoon.
Place rounded tablespoonfuls of the dough onto a lined baking sheet, 2 inches apart. Try to make sure there is a piece of banana and chocolate chip in each one.
Next, use the palm of your hand or the bottom of a glass to gently flatten the mounds of dough.
Bake for 11 to 13 minutes, or until Cookies begin to slightly brown on the bottom.
Transfer the Cookies to a wire rack to cool.