Prepare Crust: Preheat oven to 350°. Pulse first 3 ingredients in a food processor 4 to 5 times. Transfer crumb mixture to a medium bowl; stir in 1/2 cup melted butter. Press on bottom, up sides, and onto rim of a lightly greased (with cooking spray) 9-inch deep-dish pie plate. Bake 10 minutes. Cool on a wire rack. Prepare Filling: Whisk together 3/4 cup sugar and next 3 ingredients 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 just until mixture begins to boil. Cook, whisking constantly, 1 more minute; remove from heat. Whisk in semisweet chocolate and next 3 ingredients. Place plastic wrap directly on warm filling. Let stand 30 minutes. Spread filling in cooled crust; place plastic wrap directly on filling, and chill 30 minutes. Prepare Mousse: Microwave milk chocolate morsels and 3 Tbsp. heavy cream in a medium bowl at MEDIUM (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 at medium-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 filling. Cover and chill 8 to 24 hours or until set. Top with Chocolate Whipped Cream just before serving.Note: We tested with Ghirardelli Semi-Sweet Chocolate Baking Bar and Ghirardelli 60% Cacao Bittersweet Chocolate Baking Bar.