Prepare the crust: In a medium bowl, combine crushed cookies or graham cracker crumbs, melted butter, and granulated sugar. Press the mixture firmly into the bottom and up the sides of a 9-inch pie plate.
Chill the crust for at least 15 minutes while you prepare the filling.
Make the filling: In a large bowl, beat the softened cream cheese until smooth. Add the peanut butter and beat until well combined.
Gradually beat in the sweetened condensed milk and vanilla extract until the mixture is smooth and creamy.
In a separate bowl, whip the heavy cream and powdered sugar until stiff peaks form.
Gently fold about one-third of the whipped cream into the peanut butter mixture to lighten it. Then, fold in the remaining whipped cream until just combined. Do not overmix.
Pour the peanut butter filling into the chilled crust and spread evenly.
Cover the pie loosely with plastic wrap and refrigerate for at least 4 hours, or until firm. For best results, chill overnight.
Before serving, add your desired toppings such as chopped peanut butter cups or a drizzle of chocolate ganache.
Notes
For a firmer pie, you can add 1 teaspoon of unflavored gelatin dissolved in 2 tablespoons of hot water to the peanut butter filling before folding in the whipped cream.
This pie freezes well. Wrap it tightly in plastic wrap and then foil. Thaw in the refrigerator for several hours before serving.
If using peanut butter cups as a topping, chop them before adding.
For a chocolate ganache drizzle, heat ½ cup heavy cream until simmering, then pour over 1 cup of chopped semi-sweet chocolate. Let sit for 5 minutes, then stir until smooth.