Preheat your oven to 375 degrees F. Line a baking sheet with parchment paper. Set aside.
Combine the all-purpose flour, cake flour, cocoa powder, baking powder, salt, and baking soda in a medium sized bowl. Whisk together. Set aside.
In a stand mixer fitted with the paddle attachment, combine the cold butter and sugars and beat on medium speed until light and fluffy, about 2 minutes.
Add the whole egg and egg yolk and mix until combined. Scrape down the sides of the bowl and mix again for about 30 more seconds.
Turn the mixer on low speed and add the dry ingredients in three separate additions, only mixing until the dry ingredients are incorporated.
Stir in the chocolate chips and mint pieces.
Using a 2" cookie scoop, create about 16 to 18 cookies. Bake for 7 to 10 minutes. I like the cookies to be slightly underdone, so I bake at 7 minutes. Let the cookies rest for about 10 minutes before digging in.