In a  small bowl, add the flour, cocoa powder, baking soda, and salt. Whisk together and set aside.

In a mixing bowl, cream the butter for about 1 minute on high speed using an electric hand mixer.

Beat in the sugar, brown sugar, and peanut butter until well combined. Add the egg and vanilla extract, and beat on medium speed until all is combined. 

Add the flour mixture to the bowl. Using the mixer on Low, combine the ingredients until a dough is formed. It will be a little bit thick, but not too thick for an electric mixer to handle. Once it's all combined, scrape down the sides, and cover the bowl. Refrigerate for about 1 hour.

Preheat the oven to 350 degrees Fahrenheit. Line a cookie sheet with parchment or a silicone baking mat. 

With your hands, roll the dough into balls using about 1 1/2 tablespoons of dough for each ball. Place on the cookie sheet with about 2 inches between each ball. 

Bake for 9-11 minutes. Once you remove them from the oven, you can use the bottom of a glass to gently press down on each cookie. Press 2-3 dark chocolate chips into each cookie. 

Transfer each cookie to a cooling rack positioned on top of a cookie sheet. 

Put 2 tablespoons of peanut butter in a microwavable dish, and melt on high for about 10 seconds. Using a spoon, drizzle randomly over the cookies. Let the drizzle set, then store in a covered container.