In a medium bowl, whisk together flour, baking powder, salt, and cinnamon; set aside.
In the bowl of a stand mixer fitted with a paddle attachment, cream together butter and sugar until fluffy, about 3 minutes. Beat in banana and egg. Beat in dry ingredients until just combined, followed by oats. Use a rubber spatula to fold in peanut butter and chocolate chips. Cover dough with plastic wrap and let chill in refrigerator for 30 minutes.
Adjust oven racks to upper-middle and lower-middle positions and preheat to 350°F. Line two baking sheets with parchment paper. Use cookie scoop to drop dough onto prepared baking sheets. Bake until cookies are golden at the edges, about 20 minutes. Let cool 5 minutes then transfer to a wire rack to finish cooling.
