In a medium bowl, combine crushed cookies and melted butter. Press into the bottom of a 9-inch springform pan. Chill in the refrigerator while preparing the filling.
In a large bowl, beat the cream cheese and sugar until smooth and creamy.
Add melted chocolate and vanilla extract to the cream cheese mixture. Mix until fully incorporated.
Fold in the whipped topping gently until well blended.
Spread the filling evenly over the prepared crust. Smooth the top with a spatula.
Refrigerate for at least 6 hours, or until firm. Serve chilled.