Preheat the oven to 350 degrees
Beat the butter and peanut butter together until it is well combined.
Add in the sugars and cream for about 2 minutes or until the mixture has lightened.
Stir in the egg and vanilla extract.
Add in the dry ingredients (flour, baking soda, baking powder, and salt) and stir into the mixture until well combined.
Roll the cookie dough into 1.5 inch sized balls (you'll want about 24-30 balls total). Most recently I got 28.
Place cookie dough onto a cookie sheet lines with parchment paper or a silicone liner.
Bake for 7-8 minutes until the cookies just start to crack. They'll finish baking as they cool on the pan.
Let cookies cool for about 5 minutes on the pan before transferring to a cooling rack.
Allow cookies to cool on cooling rack for about 5 minutes.
Unwrap Reese's peanut butter cups and place one on the top of each cookie.
Allow Reese's and cookies to cool completely.
Add chocolate chips to a microwave safe bowl and microwave in 30 second increments stirring after each until completely smooth.
Transfer the melted chocolate into a plastic bag and cut off the corner/tip of the bag. (I just use a small ziplock bag)
Pipe chocolate legs onto the cookie starting from the Reese's body out to the edge of the cookie.
Add a little chocolate to the back of the candy eyes and press them onto the Reese's cup.
Allow chocolate to set completely before serving.