Preheat oven to 350 degrees. In a food processor, pulse chocolate cookie crumbs, pecans, sugar and salt. Stir in melted butter. Press mixture into a lightly greased 9-inch deep-dish pie plate. Bake for 10 minutes. Cool completely.

To prepare chocolate filling, whisk together 3/4 cup sugar, cornstarch, cocoa and salt in a large saucepan. Whisk together half-and-half and egg yolks in a large bowl. Gradually whisk egg mixture into sugar mixture.

Cook over medium heat, whisking constantly, 6 to 8 minutes or until mixture just begins to boil. Cook, whisking constantly, for 1 more minute. Remove from heat and whisk in semisweet chocolate, bittersweet chocolate, butter and vanilla. Place plastic wrap directly on warm filling. Let stand 30 minutes. Spread filling over cooled crust. Place plastic wrap directly ever filling and refrigerate for 30 minutes.

To prepare mousse, microwave milk chocolate chips and 3 tablespoons heavy cream in a medium bowl at 50% power for 1 to 1 1/2 minutes or until melted, stirring at 30-second intervals. Let stand 30 minutes, stirring occasionally.

Beat 1 cup heavy cream and 2 tablespoons sugar at high speed with an electric mixer until soft peaks form. Gently fold half of whipped cream into milk chocolate mixture until blended and smooth. Fold in remaining whipped cream. Spread mousse over chocolate filling. Cover and chill 8 to 24 hours or until set.

Meanwhile, prepare the chocolate whipped cream by adding 2 cups heavy cream and chocolate syrup to a large bowl. Beat at high speed with an electric mixer until foamy. Gradually beat in sugar. Continue beating until soft peaks form. Top pie with chocolate whipped cream before serving. Garnish with chocolate curls, if desired.