Prepare cake according to pkg directions. Bake in 3-8in pans.Bake at 325 for 20-25 minutes
Beat cream cheese, powder sugar and granulate sugar at med. speed until mixture becomes creamy. Fold in shredded hershey bars and cool whip. Save enough chocolate to sprinkle on outside of cake. Frost inbetween each layer and outside of cake.Refrigerate for at least 1 hour.