2/3cupunsweetened natural cocoa powder(such as Hershey's)
1cupunsalted butter, softened (I use European butter, such as Kerrygold)
3/4cuplight brown sugar, lightly packed
2cupspeanut butter chips(plus additional for decorating, if desired)
Preheat oven to 350 degrees F.
Sift together flour, cocoa powder, baking soda, and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream together butter, brown sugar, and granulated sugar until light and fluffy, 3-4 minutes. Beat in vanilla and egg. Scrape the bowl.
Gradually add the flour mixture, mixing on low speed until combined. Scrape the bowl occasionally. Mix in peanut butter chips by hand with a spatula or wooden spoon.
Scoop the dough into 24 portions onto parchment-lined baking sheets, spaced 2-inches apart. Bake for 8-12 minutes, until the center is set, but still fudgy.* For the best results, don't overbake.
Let cookies cool for 5-8 minutes on the baking sheets before transferring with a thin spatula to wire racks to cool completely. If desired, press a few extra peanut butter chips into the tops of the cookies while they're warm for decoration. Store at room temperature in an airtight container for up to 3 days.
* I've found that the baking time for this cookie varied a bit by the brand of baking sheet I was using--keep an eye on your first batch and adjust accordingly.
For a cookie with more chocolate flavor and less peanut butter, use 1 cup semisweet chocolate chips and 1 cup peanut butter chips.