In the bowl of a food processor pulse the chocolate wafer cookies until finely ground. Add butter and vanilla, pulse until mixture resembles wet sand. Using the bottom of a dry measuring cup or a glass, press crumb mixture into the bottom and up the sides of a 9-inch glass pie dish. Freeze while preparing filling. Crust can be prepared 1 week ahead of time, cover and keep in freezer.
For the filling:
Preheat oven to 350 degrees F. Combine butter, brown sugar, and corn syrup in a heavy medium saucepan. Bring to a boil, stirring often. Boil 1 minute. Stir in nuts and cream. Boil until mixture thickens slightly, about 3 minutes longer. Remove from heat. Add chocolate and stir until chocolate melts and mixture is well blended.
Pour hot filling into crust. Spread pecans evenly. Place pie dish on a rimmed baking sheet and bake until filling is bubbling all over, about 10 minutes. Transfer pie dish to rack and cool completely.