Preheat oven to 350°F (177°C) and line two large baking sheets with parchment paper or silicone baking mats.

In a medium bowl, whisk the egg until beaten. Mix in the peanut butter, then the brown sugar, baking soda, and cocoa powder. Mix everything together very well, then mix in the vanilla extract. Finally, fold in the peanut butter chips until combined.

Scoop the dough, about 1.5 Tablespoons each (I like using this medium cookie scoop), onto prepared baking sheet. Bake two batches – 6-7 cookies on each baking sheet each. Gently press down on the dough mounds with the back of a spoon. If you find the cookie dough balls are a little oily from your peanut butter (mine usually are), blot each with a paper towel.

Bake for 9-10 minutes. The cookies will look very soft—that’s ok! For crispier cookies, bake up to 11-12 minutes. Allow the cookies to cool for 10 minutes on the baking sheet before transferring to a wire rack to cool completely. Sometimes I press a couple more peanut butter chips into the tops of each cookie immediately after coming out of the oven. This is optional and only for looks!