1. Sprinkle gelatin over cold water in small bowl; let stand 2 minutes to soften. Add boiling water; stir until gelatin is completely dissolved and mixture is clear. Cool slightly.
2. Mix sugar and cocoa in large bowl; add whipping cream and vanilla. Beat on medium speed, scraping bottom of bowl often, until mixture is stiff. Pour in gelatin mixture; beat until well blended.
3. Spoon into crust. Refrigerate about 3 hours. Garnish with whipped cream and chocolates. Store covered in refrigerator. 6 to 8 servings.