Prepare the crust:
a. In a medium bowl, combine the graham cracker crumbs, sugar, and melted butter. Stir until the mixture is evenly moistened.
b. Press the mixture firmly into the bottom of a 9-inch pie dish to form a crust. Use the back of a spoon to pack it tightly.
c. Refrigerate the crust while preparing the filling.

Make the filling:
a. In a large bowl, beat together the peanut butter, marshmallow fluff, cream cheese, powdered sugar, and vanilla extract until smooth and creamy.
b. Gently fold in the whipped heavy cream until the mixture is light and fluffy.
c. Pour the peanut butter and marshmallow mixture into the prepared crust and spread it evenly.

Chill the pie:
a. Refrigerate the pie for at least 4 hours, or until it is firm and set.

Optional topping:
a. Before serving, top the pie with mini marshmallows and chopped peanuts, if desired, for added texture and flavor.

Serve:
a. Slice the pie and serve chilled. Enjoy this creamy, peanut buttery dessert!