Add the butter and sugars to a large mixing bowl. Use an electric mixer to beat them together on medium speed for about 2-3 minutes. Once creamed, add in the peanut butter and mix again on medium speed until combined.
Then, add the egg and vanilla extract and beat on a low speed until just combined.
Add in the flour, baking soda and salt. Mix again on a low speed.
Shape the cookie dough into a disc and wrap in plastic wrap. Place in the refrigerator for one hour to chill. Place the mini reese’s cups in the refrigerator to also chill.
After the cookie dough has been chilling for one hour, preheat the oven to 350℉ and line two baking sheets with parchment paper.
Create 1-inch balls of dough and place them on the baking sheet about two inches apart. Bake each sheet of cookies one at a time one the middle rack for 10-11 minutes, just until the cookies begin to crack. While the cookies bake, unwrap the reese’s cups and then keep in the refrigerator until use.
As soon as the cookies come out of the oven, gently press a reese’s cup into the center of a cookie. Then, move the cookies to a cooling rack.
Once the cookies are cool, pipe on the spider’s legs. Create eight legs by drawing four lines from the reese’s cup outward and down the cookie on each side. Dab two spots of icing to glue the eyes to the body of the reese’s cups.
To Store: Store cookies in an airtight container at room temperature for 3 -5 days.
To Freeze: Once cooled, store cookies in a freezer-safe bag or container for up to 3 months.
If using a handheld electric mixer or a mixing bowl with low sides, start mixing the butter and sugar together on a low speed for 30 seconds, until the butter and sugar begin to hold together. Then, increase to medium speed. You want to start on a low speed so that the sugar doesn’t fly out of the bowl.
For a more moist cookie, lower the flour amount to 1 ¾ cups of flour. However, the reduced amount of flour won’t produce the same lifted dome that you'll get from the extra couple tablespoons.
Don’t skip on chilling the Reese’s cups. If you add room temperature Reese’s onto a warm cookie, it will melt.
Wait to unwrap the Reese's until after they've been chilled in the refrigerator. Some of the chocolate will peel away with the wrapper of the mini Reese’s cups when you unwrap them. The Reese’s will stay more intact if they are unwrapped chilled vs unwrapped at room temperature.
If you forget to chill the Reese’s cups for an hour in the fridge, pop them in the freezer for 10 minutes. Either way, just make sure that they’re chilled and not room temperature!
Room temperature butter is ideal for this recipe.
The cookies will still be soft when they come out of the oven. It’s OK if the tops haven’t cracked when you take them out, but if they’re cracked at 10 minutes, they’re ready. They’ll continue to cook for a minute or two more while you’re placing the Reese’s cups in them, and then will firm up as they cool. Make sure the cookies are fully cooled down before decorating them with the icing.