Preheat oven to 350°.
To prepare crust, place cookies in a food processor; process until finely ground. Add 2 tablespoons brown sugar and 1 tablespoon butter; pulse 2 to 3 times or just until combined. Press crumb mixture into bottom and up sides of a 9-inch pie plate coated with cooking spray. Bake at 350° for 10 minutes; cool completely on a wire rack.
To prepare praline, combine 1/4 cup brown sugar, half-and-half, and 2 tablespoons butter in a small saucepan. Bring to a boil over medium-high heat, stirring occasionally. Cook 3 minutes without stirring. Remove from heat; add powdered sugar, stirring with a whisk. Spoon praline mixture into prepared crust; chill 30 minutes or until completely cool.
To prepare filling, combine granulated sugar, cornstarch, salt, and egg in a medium bowl; stir well with a whisk. Heat milk over medium-high heat in a small, heavy saucepan to 180° or until tiny bubbles form around edge (do not boil). Gradually add hot milk to sugar mixture, stirring constantly with a whisk. Place mixture in pan; bring mixture to a boil, stirring constantly. Cook 1 minute, stirring constantly.
Remove from heat. Spoon custard into a bowl; place bowl in a large ice-filled bowl for 15 minutes or until custard comes to room temperature, stirring occasionally. Remove bowl from ice. Stir in vanilla; spoon mixture evenly over chilled praline layer. Cover and chill 8 hours or until firm.