Make the crust: Pulse Oreo cookies, with their filling, in a food processor until finely ground. In a medium bowl, mix together crumbs and melted butter until combined and moistened. Press the mixture onto the bottom and up the sides of a 9-inch pie or tart pan. I recommend baking the crust to make it crunchy. If you choose to do so, bake in a 350F/180C preheated oven for about 8 minutes until fragrant and firm, then let it cool completely on a wire rack. If you prefer a no-bake dessert, just place it in the fridge for 30-60 minutes to firm up before adding the filling.
For the peanut butter filling: In a large bowl using a mixer fitted with a paddle attachment, beat cream cheese and peanut butter on medium-high speed until combined and smooth. Add powdered sugar and beat until combined and fluffy. Beat in vanilla extract. Set aside.
In a medium bowl using an electric mixer fitted with the whisk attachment, whisk heavy cream until soft peaks form; they should hold their shape but have a soft texture. Using a spatula, gently fold half of the whipped cream into the peanut butter mixture, then fold in the other half.
Pour filling into the pan over the crust and smooth the top. You can glaze the pie with chocolate ganache (half of the recipe will do), and/or top with peanut butter cups, peanuts, or whipped cream.
Cover pan loosely with plastic wrap and place in the fridge for at least 4 hours, or until completely set, before serving. Serve cold.
Peanut butter pie will keep for 3-4 days in the fridge.