Step 1: Crush the entire package of Oreo cookies (with the cream filling) into fine crumbs. Mix these crumbs thoroughly with the melted butter. Press the mixture firmly into the bottom of a 9x13 inch baking dish. Place in the freezer while you prepare the next layer.
Step 2: In a large bowl, beat the softened cream cheese with powdered sugar until light and fluffy. Gradually beat in 1/2 cup of cold milk until smooth. Gently fold in half of the whipped topping until just combined. Spread this creamy mixture evenly over the chilled Oreo crust.
Step 3: In a separate bowl, whisk together the instant chocolate pudding mixes with 3 cups of cold milk until thickened, about 2-3 minutes. Allow it to sit for a minute or two to thicken further. Spread this chocolate pudding layer over the cream cheese layer.
Step 4: Drizzle about half of the caramel topping over the chocolate pudding layer. Sprinkle about half of the toasted pecan pieces over the caramel.
Step 5: Spread the remaining half of the whipped topping over the caramel and pecan layer. Smooth it out gently.
Step 6: Drizzle the remaining caramel topping decoratively over the top of the whipped topping. Sprinkle the remaining toasted pecan pieces over the caramel.
Step 7: Cover the dish tightly with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the layers to set properly and the flavors to meld beautifully. Slice and serve chilled.