Line cookie sheet with parchment paper.
Mix together peanut butter, butter, and vanilla.
Gradually add the powdered sugar, stirring it into the mixture until it is incorporated.
Roll into 1-inch balls and place on the prepared sheet.
Insert a toothpick into each ball.
Place in freezer until hard (about 30 minutes).
Combine the chocolate chips and shortening.
Melt by microwaving for 1 minute, then stirring and repeating until smooth and melted.
Use the toothpick to dip into the chocolate (leave a small circle uncoated on top of each).
Gently shake off excess and place back on sheet.
Refrigerate several hours until chocolate sets.
Remove toothpicks and smooth over the hole.