Preheat oven to 410°F. Line two baking sheets with silicone baking mats or parchment paper.
In a large bowl of a stand mixer, cream together butter and sugar on high speed until light and fluffy. Add eggs one at a time until evenly mixed in. Use a spatula to scrape the sides of the mixing bowl to ensure all the butter and sugar gets mixed in with the egg.
Add cocoa powder, cake flour, all-purpose flour, cornstarch, baking soda, and mix on the lowest speed cycle until dough forms. Be careful not to overmix. Stir in the peanut butter chips
Use your hands to grab dough and place onto scale until you have a dough ball with a weight of 6 oz. Keep your dough ball very loose. Do not compact it, roll it, or smooth it out.
Place only four cookies on each baking sheet, spacing them about 2 inches apart, 2 cookies per row in a stagged pattern. (Please see my photo above for how I spaced them.)
Bake only one sheet at a time in the middle row of the oven for 8-10 minutes or until surface looks cooked but the middle of the cookies are not fully set. Let cookies set and cool for 20-30 minutes on the baking sheet before attempting to remove them. After that, cookies should be set enough to be removed in one piece. When you break them open they should still have a melty peanut butter center.
This recipe makes 8 full 6-oz cookies with some dough leftover for one smaller cookie.
If your cookies are spreading too much, please see the blog post for details on what makes the cookies stay thick.
Because 1-2 minutes can make such a big difference in the cookie outcome, I recommend baking 1 test cookie to find the ideal time for your oven. If you cook the cookies too long they will be fully set and will not have a gooey center. If you underbake them too much, even after the cooling period, the cookies will not be set and will fall apart.
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The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.