Make the base. Preheat oven to 350°F. In a food processor or blender, pulse the Oreo cookies into fine crumbs. Transfer the crushed cookies to a bowl. Add the melted butter and stir to combine. Transfer the crumb mixture to a 9-inch pie dish and press into the bottom and sides of the dish to form a crust. Bake for 10-12 minutes. Allow the crust to cool completely before filling.
Make the pistachio pudding. In the bowl of a stand mixer fitted with the whisk attachment (or a large bowl with electric beaters), whip milk and pudding mix together on low speed for 2 minutes, until it begins to thicken slightly. Transfer the pudding to a separate bowl.
Make the filling. In the stand mixer bowl (or a separate bowl with electric beaters), beat the cream cheese and 1/4 cup confectioners' sugar together on medium-high speed until smooth and combined. Add the prepared pudding and beat together until smooth. Using a spatula, fold in the Cool Whip until combined. Spread the filling over the cooled Oreo cookie base. Chill in the refrigerator for at least 2 hours, or until ready to serve. The more time you give the filling to set the firmer it will be.
Make the whipped cream topping. In the bowl of a stand mixer fitted with the whisk attachment (or a large bowl with electric beaters), whip heavy cream and 2 tablespoons confectioners' sugar on medium-high speed until medium-to-stiff peaks form, about 3 minutes. Transfer to a piping bag fitted with a large star tip.
Serve. Pipe whipped cream swirls around the border of the pie. Sprinkle crushed pistachios over top and serve.
Notes
Storage: Store covered in the refrigerator for up to 3 days.Make it ahead: This pie can be made ahead and kept in the refrigerator until ready to use. To make it ahead, assemble the pie up to step 4 and chill until ready to use. Before serving, finish the pie off by whipping and piping on the cream and sprinkling crushed pistachios over top.