In the bowl of an electric mixer, cream together cream cheese, vanilla extract and powdered sugar. Cream it very well until no cream cheese lumps remain. Fold in crushed Oreo's and whipped topping. Cover and refrigerate until ready to serve. If it gets too thick after sitting in the fridge, stir in a tablespoon of milk at a time until it reaches the desired creamy consistency. Serve with crumbled Oreo's on top for garnish.