Preheat oven to 325º. Lightly butter a 9 inch pie plate
Crust: Add Oreos to a food process and process until finely ground. Add melted butter and process just to incorporate, with 3-4 pulses. Place in the pie plate and evenly spread it on the bottom and sides using a flat bottom dry measuring cup to pat it into place. Bake for 13 minutes. Let cool on a wire rack.
Sauce: Add sugar, water and corn syrup to a saucepan and bring to a boil over medium-high heat. Cook without stirring for 6-8 minutes until it is straw colored. Turn down the heat to medium low and continue to cook, swirling the pan occasionally until it turns an amber color, about 4-6 minutes. A thermometer should read 350º to 360º.
Remove from the heat and stir in cream. Add chocolate and butter and let it sit for a minute then whisk until it’s smooth and the chocolate has melted. Stir in pecans, vanilla and salt. Let cool slightly.
Pour 1 cup of the sauce into the baked pie crust and refrigerate until set and no longer liquid, about 1 hour. Reserve the rest for later.
Filling: With a mixer, beat cream cheese and butter until smooth. Add marshmallow cream, peanut butter and cream and mix on high until light and fluffy, 3-5 minutes. Spoon into the pie crust on top of the layer of caramel, spread evenly with an offset spatula. Refrigerate until the filling is set, about 2 hours.
Once the filling is firm to the touch, drizzle the remaining caramel mixture over the top. If it is too thick to pour, microwave it at 10 second intervals until it is pourable. Refrigerate for about 5 minutes to let the caramel set before cutting.