Place oreos in a food processor and process until finely ground. Place in a medium bowl and mix together with melted butter. Spoon into a 9-inch pie plate. Use your hands or the back of a wooden spoon to spread evenly. Press down firmly on crust. This will help it hold together. Refrigerate for at least 1 hour.
In a small heavy-bottomed saucepan, melt chocolate. Remove from heat and stir in condensed milk.
Pour on top of pie crust. Sprinkle pecans on top.
In a medium bowl, whisk together pudding mix and milk for 1 minute. Fold 1/2 cup whipped topping into pudding mixture. Pour on top of pecans.
Top with remaining whipped topping. Refrigerate until set.