Break apart your Hershey's Bars and reserve 2-4 pieces for garnishing the pie later. Place them in a microwave safe bowl and heat for 20-30 second increments until the chocolate is melted.
Add the thawed Cool Whip to the melted chocolate and mix until well combined.
Spoon the mixture into your prepared pie crust, and then use a cheese grater to garnish the top with any chocolate you have set aside.
Refrigerate and chill for at least 3 hours or overnight before slicing.