Step 1: Prepare the crust. Finely crush the entire package of Oreos in a food processor or a Ziploc bag with a rolling pin. In a medium bowl, combine the crushed Oreos with the melted unsalted butter. Press the mixture firmly into the bottom of a 9x13-inch baking dish. Place in the freezer for 10-15 minutes to set.
Step 2: Make the cream cheese layer. In a large mixing bowl, beat the softened cream cheese until smooth and creamy. Add the powdered sugar and vanilla extract (or paste) and beat until well combined and fluffy. Gently fold in the first 8 ounces of thawed Cool Whip until no streaks remain.
Step 3: Spread the cream cheese mixture evenly over the chilled Oreo crust. Return the dish to the freezer while you prepare the next layer.
Step 4: Prepare the chocolate pudding layer. In a separate large bowl, whisk together the two cans of evaporated milk and the two boxes of instant chocolate pudding mix. Whisk continuously for about 2-3 minutes until the mixture begins to thicken significantly.
Step 5: Carefully spread the thickened chocolate pudding mixture over the cream cheese layer.
Step 6: Add the final Cool Whip layer. Spread the remaining 8 ounces of thawed Cool Whip evenly over the chocolate pudding layer.
Step 7: Chill the lasagna. Cover the dish loosely with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow all layers to set completely.
Step 8: Garnish and serve. Before serving, decorate with your desired toppings such as chocolate chips, extra crushed Oreos, chocolate curls, or a drizzle of chocolate sauce. Slice and enjoy!