In a stand mixer fitted with a paddle attachment, beat together the butter, brown sugar, and granulated sugar until smooth and creamy.
Beat in the eggs, one at a time.
Pulse in the dark cocoa powder until incorporated, then mix in the all-purpose and cake flours with the baking powder and salt until just combined.
Stir in 9 ounces of the chocolate chips.
Pull off about 1/3 cup piece of dough, measuring it and adding more or less to make 4.5 ounces. Roll into a ball and place on a parchment-lined baking sheet. Repeat with the remaining dough, dividing them between two baking sheets and about 2-3 inches apart. If desired, top the cookie balls with remaining chocolate chips.
Place the baking sheets in the freezer for 1 hour.
Preheat oven to 350˚F. Bake the frozen cookies in the preheated oven until just set, about 18 minutes. Allow to cool to room temperature, about 20 minutes, and they are best eaten the day they are baked.