1 C all purpose flour (I usually use about half whole wheat)
Preheat oven to 350°F and line a baking sheet with parchment paper (I never have parchment paper in the house; I used aluminum foil that I greased very lightly).
In a small bowl, whisk together flour, baking powder, baking soda and salt.
In a large bowl, cream together the butter and the sugars. Beat in egg and banana, followed by the vanilla extract. Gradually add in the flour mixture. Stir in the oats and chocolate chips.
Drop dough by tablespoonfuls onto prepared baking sheet.
Bake for 11-14 minutes, until set and lightly browned.
Let cookies cool for about 5 minutes on the pan before transfering them to a wire rack to cool completely.
Makes 2 dozen cookies.