Preheat oven to 350°F. Lightly coat a 9-inch pie plate with cooking spray. In a medium bowl toss together butter and crushed chocolate wafer cookies. Spread into pie plate; press evenly onto bottom and up sides. Bake for 5 minutes. Cool on a wire rack.
In a large bowl beat cream cheese and sugar with an electric mixer on medium speed until combined. Add eggs, one at a time, beating on low speed after each addition just until combined. Stir in pumpkin, vanilla, pumpkin pie spice, and salt. Pour pumpkin mixture into baked crust.
Bake about 40 minutes more or until mixture is slightly puffed around edges and just set in center. Cool on a wire rack for 1 hour.
In a small microwave-safe bowl combine dark chocolate and cream. Microwave on 100 percent power (high) for 30 seconds to 1 minute; stir until smooth. Let stand for 15 minutes. Pour chocolate mixture over the cooled pie, spreading evenly. Chill, uncovered, for 1 hour. Cover and chill for 2 to 24 hours more. If desired, drizzle with milk chocolate.
Prepare as directed. Cover and chill for up to 48 hours.