In a large bowl whisk together the flour, cake flour, cocoa, baking powder, baking soda and salt. Set aside.
In a separate large bowl beat together the butter, brown sugar, and white sugar until fluffy.
Beat in the eggs and vanilla extract.
Mix the dry ingredients into the butter mixture about 1/2 at a time. I typically do a few stirs by hand with a rubber spatula first, then turn the mixer to a low speed and gradually increase to a medium speed until combined. The batter will be very thick.
Stir in the peanut butter chips.
Cover the bowl with plastic and place in the fridge for at least 2 hours or up to 48 hours.
When ready to bake, preheat the oven to 375F (190C) degrees and line cookie sheets with parchment paper.
Form the dough into balls using about 1/4 to 1/3 cup per cookie - or weigh each cookie so that each is around 4 ounces (112 grams). If the dough is too hard to work with, let it sit on the counter for 10 minutes first. Place the cookies at least 2 inches apart on the lined cookie sheets.
Bake the cookies 1 tray at a time on the middle rack of the oven for 12-14 minutes, or until the tops look just set.
Remove from the oven. Allow the cookies to cool on the tray for at least 20 minutes. The cookies will continue to bake as they cool on the tray.