Place chocolate chips in a glass bowl along with half of the whipping cream and microwave on high at 1 minute intervals until chocolate melts and mixture is smooth
Allow mixture to cool
Meanwhile, beat remainder of whipping cream until soft peaks form
Add vanilla and sugar and continue beating
Slowly add chocolate mixture and mix well
Place in the chocolate piecrust and refrigerate for several hours before serving
Notes
Use low fat chocolate whipping cream and your favorite sugar substitute