Place crumbs and sugar in a medium bowl and stir in butter until evenly blended. Press crumb mixture firmly on bottom and up sides of 9-1/2-inch pie plate. Bake 10 minutes. Cool.
Melt chocolate. Whisk together 1/2 cup milk and cornstarch. Set aside. Bring remaining 1 1/2 cups milk, sugar, cocoa and salt just to a simmer over medium heat, stirring frequently. Stir cornstarch mixture then add to milk mixture in saucepot and bring to a boil, whisking constantly. Once mixture is at a boil and quite thick, cook 1 additional minute. Remove from heat and stir in melted chocolate and vanilla. Spoon into cooled crust. Cover surface directly with plastic wrap to prevent skin from forming. Chill at least 4 hours or overnight.
Puree 1/2 package of raspberries in food processor fitted with metal blade. Strain through a fine mesh strainer. Discard seeds. Stir sugar into puree until disolved.
Beat heavy cream and sugar until stiff peaks just form. Stir in vanilla. Spread whipped cream topping on chilled pie. With a small spoon drop small amounts of raspberry puree onto whipped cream. Use a toothpick or sharp knife to swirl puree into cream. Top with remaining raspberries.