Triple Chocolate Mousse Torte

Pulse cookies in a food processor until fine crumbs form. Add melted butter; pulse until combined. Press onto bottom of a greased 9-in. springform pan. Refrigerate while preparing filling., In a small saucepan, sprinkle 2 teaspoons gelatin over 1 tablespoon cold water; let stand 1 minute. Heat and stir over low heat until gelatin is completely dissolved; remove from heat., Place bittersweet chocolate and 1/2 cup cream in a metal bowl over a small saucepan of hot water; heat and stir until mixture is smooth. Stir in gelatin mixture. Transfer to a medium bowl; cool completely. Repeat twice with milk and white chocolates., In a large bowl, beat vanilla and remaining 3 cups cream until stiff peaks form. Fold 2 cups whipped cream (a third of the total whipped cream) into cooled bittersweet chocolate; spread over crust. Refrigerate until set, 25-30 minutes. Repeat twice with milk and white chocolates, keeping remaining whipped cream chilled until needed., Refrigerate torte, covered, until set, about 4 hours. To serve, loosen sides from pan with a knife. Carefully remove rim from pan.