Preheat oven to 375.
In a large bowl, beat together shortening, peanut butter, egg, sugar, brown sugar, vanilla, and milk.
In a medium bowl, whisk together flour, baking soda, and salt.
Gradually add dry mixture to wet mixture and beat until blended.
Form into 1″ balls.
Roll in sugar and place a couple of inches apart on ungreased cookie sheet.
Bake 10-12 minutes or until golden.
Immediately, gently press an upside down frozen peanut butter cup on top of each cookie and move to wire rack to cool.
After placing and moving all of the cookies on the wire rack, put in place the candy eyes while chocolate is still slightly soft.
Place in refrigerator for 10 minutes to allow cookies to firm.
Put chocolate chips in the corner of zippered sandwich bag.
Microwave for 20 seconds, knead and repeat until chocolate has melted.
Clip tiny piece off of the corner of bag to allow for piping and draw eight legs on each spider cookie.
Place in refrigerator for 10 minutes to allow legs to set.