Preheat the oven: Preheat the oven to 375°F. Line 2 baking sheets with parchment paper or silicone baking mats and set aside.
Cream the butter and sugars: Add the cubed butter, dark brown sugar, and granulated sugar to the bowl of a stand mixer fitted with the paddle attachment. Cream on medium speed until combined and creamy, about 3-4 minutes Start Timer. Scrape down the sides of the bowl as needed.
1 cup unsalted butter, 1 cup dark brown sugar, 3/4 cup granulated sugar
Add the wet ingredients: Add the eggs and vanilla and mix until combined, scraping down the sides of the bowl as needed.
2 large eggs, 1 Tbsp. vanilla extract
Add the dry ingredients: Add the flour, cocoa powder, cornstarch, baking soda, baking powder, and salt. Mix on low just until the flour is incorporated. Be careful not to overmix.
2⅔ cups all-purpose flour, 1/2 cup extra dark cocoa powder, 2 tsp. cornstarch, 1 tsp. baking soda, 1 tsp. baking powder, 3/4 tsp. fine salt
Add the peanut butter chips: Fold in the peanut butter chips until evenly distributed throughout the dough.
1 (11 oz.) bag peanut butter chips
Shape: Portion the cookie dough into large balls, about 5-6 oz. each (you should get ~10 cookies). Keep the cookie dough balls tall rather than perfectly round to help create thick bakery-style cookies. I pinch the dough with my fingertips to give them a rustic look with the bumps on top.
Bake: Place 5 cookies on each prepared baking sheet, leaving plenty of space between them. Bake for 10-12 minutes Start Timer, or until the edges are set but the centers still look slightly underbaked. I always underbake them because they will continue to set up on the cookie sheet once you remove them from the oven.
Cool: (Tip: right after baking, if any cookies look wonky, just take the back of a spoon and gently press the cookie dough back into a circular shape. But they shouldn’t overly spread.) Immediately after removing from the oven, press a few more peanut butter chips into the tops for that bakery-style look. Sprinkle with flaky sea salt. Allow the cookies to cool on the baking sheet for about 10-15 minutes before transferring to a wire rack.
Maldon flaky sea salt