In the bowl of a stand mixer, with the paddle attachment affixed, add the butter, banana, brown sugar and white sugar. Mix on medium-high until the ingredients are thoroughly combined. Change the mixer to low and add the vanilla extract, salt and nutmeg. Mix until combined.

With the mixer on low, add the flour, baking soda and cornstarch. Mix until barely combined. Remove the bowl from the mixer and use a rubber scraper to ensure all the ingredients are incorporated. Fold in the chocolate chips.

Line a large cookie sheet with parchment paper or a baking mat. Use a 1/4-cup scoop to scoop seven cookie dough balls and drop the cookie dough balls onto the prepared cookie sheet. Place cookie dough balls in the refrigerator to chill for one hour before baking.

Once cookie dough has chilled, preheat oven to 350-degrees and bake cookies for 13-14 minutes or until the edges are lightly browned. Remove from oven and let cookies set on the cookie sheet for 10-minutes before transferring to a wire rack to finish cooling.