Preheat the oven: Preheat the oven to 350°F (177°C). Line two large baking sheets with parchment paper.
Cream butter, peanut butter & sugars: In the bowl of a stand mixer fitted with the paddle attachment, combine the cold cubed butter, peanut butter, dark brown sugar, and granulated sugar. Beat on medium-high speed for 2-3 minutes, or until well combined and slightly fluffy.
1 cup unsalted butter, 1 cup creamy peanut butter, 1 cup dark brown sugar, 3/4 cup granulated sugar
Add eggs & vanilla: Mix in the egg, yolks, and vanilla extract until smooth and creamy, scraping down the sides of the bowl as needed.
2 large egg yolks + 1 large egg, 2 tsp. vanilla extract
Add dry ingredients: In a separate bowl, whisk together the flour, baking soda, baking powder, cornstarch, and salt.
3 cups all-purpose flour, 1 tsp. baking soda, 2 tsp. baking powder, 2 tsp. cornstarch, 1/2 tsp. salt
Combine ingredients: Gradually add the dry mixture to the wet ingredients, mixing on low speed until just combined. Do not over-mix. The dough should be thick and slightly tacky.
Add chocolate chips: Fold in the dark chocolate chips until evenly distributed.
2½ cups dark chocolate chips
Portion the dough: Grab the dough and place it on the baking sheet. I like to keep the cookies looking rustic, so I don’t roll in a ball; to make them bakery style, I keep them in tall mounds and use my fingertips to pinch them a little. Trust me, it makes the perfect-looking cookie just like my Kroll’s Kookies!
Bake: Bake for 10–13 minutes, or until edges are lightly golden and centers look soft and slightly underbaked. The cookies will continue to set as they cool. Start Timer
Cool & set: Let cookies cool on the baking sheet for 15 minutes before transferring to a wire rack to cool completely. The centers will firm up into that signature thick, gooey Levain texture.