In a stand mixer with a paddle attachment or large bowl with a hand mixer, beat the cold butter and sugars on low for 30 seconds, then increase to medium-high speed for 3-4 minutes. Once it is very light and fluffy, scrape the bowl.
1 cup butter, 1 cup brown sugar, ½ cup sugar
Beat in the eggs on medium-low speed one at a time, then scrape the bowl well.
2 eggs
In another medium bowl, combine the dry ingredients. Add the flour mixture to the butter mixture and combine on low until just combined.
½ cup dark cocoa powder, 1½ cups cake flour, 1 cup all-purpose flour, 1 teaspoon cornstarch, ¾ teaspoon baking soda, ½ teaspoon kosher salt
Add the peanut butter chips and combine on low until evenly distributed, being careful not to overmix.
1⅓ cups peanut butter chips
Using a 3.25 ounce scoop (or ⅓ cup measuring cup plus one tablespoon of dough), scoop cookies onto a sheet pan lined with parchment paper. Use a flat measuring cup to gently flatten the cookie to about ¾ inch thick (see picture). Freeze the prepared cookies for 30 minutes on the sheet pan.
While freezing, preheat the oven to 410°F and line a second sheet pan with parchment. Once chilled, bake one cookie sheet at a time (each pan hold 5-6 cookies) for 9-10 minutes, until the edges look set and the top is mostly dry. Cool for 10 minutes on the sheet pan.