Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, baking soda, salt, and cocoa powder.
In a large bowl, beat together the softened butter, granulated sugar, and brown sugar until creamy.
Add the peanut butter, egg, and vanilla extract, mixing until well combined.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the chocolate chips.
In a small bowl, mix the peanut butter and powdered sugar until smooth.
Using a tablespoon, drop rounded balls of cookie dough onto the prepared baking sheet, leaving space between each.
Using a small spoon or knife, swirl a bit of the peanut butter mixture into each cookie dough ball.
Bake for 10-12 minutes or until the edges are set.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.