Unrap around 24 mini reese's cup candies and place in the freezer for at least 2 hours prior to baking. This will help them hold their shape once placed on the hot cookies.
Preheat oven to 350°F
In a mixing bowl, combine the butter, sugar, and brown sugar. Beat with an electric mixer or in a stand mixer for 2-3 minutes until fully creamed.
Add in the peanut butter, egg, and vanilla extract, and beat again until combined.
In a separate bowl, whisk together the flour, baking soda, baking powder, and salt.
Add the flour mixture into the mixing bowl and mix on low or with a spatula until just combined. Do not overmix
Using a small cookie scoop form balls about 1 1/2 tablespoon from the dough. Roll the dough between you hands to get a uniform ball, then roll in a bowl of granulated sugar. Place the balls 2-3 inches apart on a silicone lined baking sheet and bake for 9-11 minutes or until the edges of the cookies start to brown and crack.
Remove the cookies from the oven and immediately place a frozen mini Reese's cup into the center of each cookie, pressing down lightly. Allow the cookies to cool for 15-20 minutes before moving to a cooling rack.
Place chocolate chips in a microwave safe bowl. On 50% power, microwave for 2-3 minutes stirring the chocolate every 45 seconds to prevent burning. When fully melted transfer to a piping bag or plastic sandwich bag with the corn cut off.
Draw 4 legs on each side of the cookies. Place a small dot of melted chocolate on the mini Reese's and place 2 eyes on the spider cookies. Allow the chocolate to fully set before arranging on a serving platter.