Mix peanut butter, sugar, butter and vanilla together in a large bowl. Cover and refrigerate for 1 hour.
Melt chocolate chips and shortening over low heat (I use my crockpot). Make peanut butter mixture into 1 inch to 1 1/2 inch balls. Work with a small amount of the peanut butter mixture at a time, keeping the rest refrigerated until ready to form into balls. Using toothpicks or small forks, dip the balls into the chocolate. Set on wax paper and refrigerate.