Mix all of the peanut butter frosting ingredients in a bowl and set aside as you prepare the cookies. Chop reese's and also add these to a bowl and pop in the fridge so it doesn't melt.
In a medium-sized bowl add flour, cocoa powder, and baking soda and whisk together.
In another bowl, add the softened butter, sugar, eggs, and vanilla extract. Once fully mixed together add the chocolate chips. Use your cookie scoop to place cookies 1 inch apart on your parchment paper linked baking sheet. Cook at 350 for 15-20 minutes (depending on your oven temp). Use a toothpick to poke a cookie and see if they're fully cooked. Place the cookies on a wire rack until fully cooled.
Add the peanut butter frosting to a piping bag and swirl it on top of the brownie cookie. Add some chopped Reese's on top of each cookie