1. Set aside 2 tablespoons chocolate chips and 1 tablespoon nut pieces. Place remaining chips, nuts and 3 tablespoons whipping cream in medium microwave-safe bowl. Microwave at MEDIUM (50%) 1 minute; stir. If necessary, microwave at MEDIUM an additional 15 seconds at a time, stirring after each heating, until chips are melted when stirred. Spread mixture on bottom of crust. Refrigerate while preparing next steps.
2. Sprinkle gelatin over cold water; let stand 1 minute to soften. Add boiling water; stir until gelatin is completely dissolved and mixture is clear. Cool slightly, about 5 minutes.
3. Meanwhile, stir together sugar and cocoa in small mixing bowl; add remaining 1 cup whipping cream and vanilla. Beat on medium speed of electric mixer, scraping bottom of bowl occasionally, until stiff. Pour in gelatin mixture, beating until just well blended.
4. Carefully spread over chocolate layer in crust. Cover; refrigerate several hours or until firm. Garnish with whipped cream and remaining chip and nut mixture. 6 to 8 servings.