Preheat oven to 350°.
To prepare crust, place cookies in a food processor; pulse until crumbs form to measure 1 1/4 cups. Add melted butter and egg white; pulse until moist.
Spoon crumb mixture into a 9-inch round removable-bottom tart pan coated with cooking spray. Press into bottom and up sides of pan. Bake at 350° for 9 minutes or until golden brown. Cool on a wire rack.
To prepare filling, heat 1 1/2 cups milk in a heavy saucepan over medium-high heat to 180° or until tiny bubbles form around edge (do not boil). Remove from heat. Combine 1/2 cup milk, sugar, cornstarch, salt, and egg in a large bowl, stirring with a whisk. Gradually add hot milk, stirring constantly with a whisk.
Place mixture in pan. Cook over medium heat until thick (about 3 minutes), stirring constantly. Reduce heat to low; cook 2 minutes, stirring constantly. Remove from heat; stir in liqueur, 1 tablespoon butter, rind, and vanilla. Pour into prepared crust; cover surface with plastic wrap. Chill 8 hours or until set. Remove plastic wrap. Spread whipped topping evenly over filling. Sprinkle with nuts.