Start by crushing Oreo cookies in a food processor until they resemble fine crumbs. In a mixing bowl, combine the crushed cookies with melted butter, stirring until well mixed. Firmly press this mixture into the bottom of a springform pan to create an even layer.

In a large bowl, use an electric mixer to beat the softened cream cheese and powdered sugar together until smooth, about 2-3 minutes. Melt the semi-sweet chocolate until smooth, then let it cool slightly. Stir the melted chocolate and cocoa powder into the cream cheese mixture.

Gently fold in the whipped topping into the chocolate cream cheese mixture using a spatula.

Pour the cheesecake filling onto the prepared Oreo crust. Smooth the top evenly and cover with plastic wrap. Refrigerate for a minimum of four hours.

Once set, carefully remove the springform pan, slice the dessert, and serve chilled.