To make filling: Beat cream with 1/4 cup powdered sugar and vanilla, until stiff peaks form; set aside.
In another bowl, beat remaining 1 cup powdered sugar, cream cheese, peanut butter, and butter until fluffy.
Fold in half the whipped cream mixture.
Spoon cream cheese mixture into reserved crust Cover and chill 2 hours.
Spread fudge topping on pie, leaving a 1 inch border.
Rebeat reserved whipped cream mixture and spoon around border.
Chill 1 hour.