Chocolate Truffle Pie

In microwave-safe bowl, combine chocolate chips and 1/2 cup of the heavy cream. Cook on high for 1 to 2 minutes, stirring every 30 seconds until smooth. Cool to room temperature. Stir in sugar and vanilla. Set aside. In small bowl, beat the remaining heavy cream until soft peaks form. Blend in the chocolate mixture on high speed 1/3 at a time, mixing well. Spoon into prepared crust. Refrigerate several hours before serving. Garnish with fresh berries and whipped cream, if desired.