To prepare crust, combine first 3 ingredients in a bowl, tossing with a fork until moist. Press into bottom and up sides of a 9-inch pie plate coated with cooking spray. Bake at 350° for 12 minutes; cool crust on a wire rack.
To prepare the filling, combine the sugar, cornstarch, and salt in a small heavy saucepan. Gradually add the milk, stirring with a whisk until well-blended. Cook over medium heat until mixture comes to a boil; cook for 1 minute, stirring with a whisk. Gradually add about 1/3 cup hot custard to beaten eggs, stirring constantly with a whisk. Return egg mixture to pan. Cook over medium heat until thick (for about 1 minute); stir constantly. Remove from heat, and stir in peanut butter and vanilla. Cool slightly.
Arrange banana slices in bottom of prepared crust; spoon filling over bananas. Press plastic wrap onto the surface of filling; chill 4 hours. Remove plastic wrap. Spread whipped topping evenly over filling. Chill.