Step 1: Prepare the crust. In a medium bowl, combine the Oreo crumbs and melted butter until well mixed. Press the mixture firmly into the bottom of a 9x13 inch baking dish. Place in the refrigerator to chill while you prepare the next layer.
Step 2: Make the cream cheese layer. In a large mixing bowl, beat the softened cream cheese and powdered sugar with an electric mixer until smooth and creamy. Gently fold in half (8 ounces) of the thawed whipped topping until no streaks remain.
Step 3: Spread the cream cheese mixture evenly over the chilled Oreo crust.
Step 4: Prepare the chocolate pudding layer. In a separate bowl, whisk together the instant chocolate pudding mix and cold milk for about 2 minutes, or until the mixture begins to thicken. It will continue to thicken as it sits. Immediately spread the pudding evenly over the cream cheese layer.
Step 5: Sprinkle half (1/2 cup) of the chopped pecans over the chocolate pudding layer.
Step 6: Carefully spread the remaining 8 ounces of whipped topping over the pecan-topped pudding layer, gently smoothing it out to the edges.
Step 7: Drizzle the caramel sauce generously over the top of the whipped topping. Sprinkle the remaining 1/2 cup of chopped pecans over the caramel.
Step 8: Cover the baking dish tightly with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the layers to set completely.