Preheat oven to 350 degrees. Use parchment paper or a silpat mat to line a baking sheet.
Cream the butter, brown sugar and granulated sugar in a stand mixer until light and fluffy (about 2-3 minutes). Scrape the sides of the bowl to make sure all ingredients are blended.
Add in the egg and vanilla and beat until combined.
Add in flour, cocoa, salt and baking soda. Mix until all combined.
Scoop out 24 equal cookie dough balls (they should be 1 TBSP of dough – I recommend a 1 TBSP cookie scoop). Place 12 cookie dough balls on each baking sheet. Slightly flatten dough balls into discs about 1" thickness.
Bake at 350 degrees for 8 minutes. (NOTE: If you are making giant cookies - cook for up to 12 minutes)
Remove cookies from over and let cool on baking tray for 10 minutes before removing to cooling rack.
Make the peanut butter layer while the cookies are cooling. Combine peanut butter, butter, powdered sugar and vanilla in a medium bowl and mix until it is a thick dough.
Divide the peanut butter mixture into 24 balls and top each cooled cookie with a peanut butter ball. Slightly press down on the peanut butter ball to flatten into a disc.
Melt the chocolate chips in the microwave in 30 second intervals until completely melted. Spoon 1-2 tsp of melted chocolate on the top of each cookie and slightly spread.
Store these cookies in an airtight container at room temperature (4 days) OR my preferred method of storing is to store them in the refrigerator for up to a week.