1. Preheat oven to 375°.
2. To prepare the crust, reserve 1 tablespoon crumbs for topping. Combine the remaining crumbs, 2 tablespoons sugar, cinnamon, and 1/8 teaspoon salt in a bowl, stirring well. Stir in egg white and butter. Press crumb mixture into bottom and up sides of a 9-inch pie plate coated with cooking spray. Bake at 375° for 9 minutes or until lightly toasted; cool completely on a wire rack.
3. To prepare filling, combine 1/2 cup sugar and the next 7 ingredients (through egg yolk) in a bowl, stirring well with a whisk. Place milk in a medium, heavy saucepan over medium-high heat; cook until milk reaches 180° or until tiny bubbles form around edge (do not boil). Gradually add hot milk to egg mixture, stirring constantly with a whisk. Return milk mixture to pan; cook over medium heat 10 minutes or until thick and bubbly, stirring constantly. Remove from heat. Add chocolate; stir until smooth.
4. Place pan in a large ice-filled bowl for 10 minutes or until mixture cools, stirring occasionally. Spoon filling into crust, and cover surface of filling with plastic wrap. Chill 3 hours or until set; remove plastic wrap. Spread whipped topping over pie; sprinkle with reserved cracker crumbs.