Make the Oreo crust. In a food processor, blend the Oreo Thins and melted salted butter until the crumbs are finely ground. Pat the mixture into the bottom and up the sides (about 1½" or so) of a 9-inch pie dish. Place the crust in the freezer to chill while you make the peanut butter filling.
1 package Oreo Thins (11.78 oz), 6 tbsp salted butter
Make the peanut butter filling. In a medium bowl, use a hand mixer to mix the creamy peanut butter, melted butter, powdered sugar, and vanilla extract until smooth. Take the pie crust out of the freezer and pour in the peanut butter filling. Use an offset spatula to smooth it into an even layer. Place the pie back in the freezer to chill.
2 cups creamy peanut butter, 8 tbsp salted butter, ¾ cup powdered sugar, ¼ tsp vanilla extract
Make the chocolate ganache. Place the semi-sweet chocolate chips, bittersweet chocolate chips, and heavy cream in a small microwave-safe bowl or measuring cup. Microwave on high for 30 seconds, then stir. Microwave for another 30 seconds on high. Then stir well until there are no lumps and the ganache looks shiny.
¼ cup semi-sweet chocolate chips, ¼ cup bittersweet chocolate chips, ⅓ cup heavy cream
Short chill. Allow both the ganache and the peanut butter pie to chill in the freezer for about 15-20 minutes. This will help the peanut butter layer set up and the ganache thicken.
Add the ganache to the peanut butter layer. Stir the ganache well. It should have thickened to an almost frosting-like consistency after being chilled. Spoon it onto the peanut butter layer of the pie and use an offset spatula to spread it into an even layer right up to the crust without covering it.
Add toppings (optional). Sprinkle chopped peanut butter cups, chocolate chips, crushed Oreos, or any other desired toppings over the ganache layer.
Long chill. Place the pie in the fridge to chill for at least 4 hours or, in the best case, overnight.
Serve. You can cut this pie right out of the fridge or sit it out on the counter for 5-10 minutes before serving for a creamier texture. Slice, serve, and enjoy!