1. Beat whipping cream, 1/2 cup powdered sugar and vanilla until stiff; set aside. Stir together remaining 1 cup powdered sugar and cocoa in small bowl.
2. Beat cream cheese in separate bowl until fluffy. Gradually beat in sugar and cocoa mixture, beating until blended. Lighten mixture by blending half of whipped cream into chocolate mixture. Fold in remaining whipped cream. Spoon into crust.
3. Refrigerate several hours or until firm. Garnish as desired. Makes 8 servings.