In a food processor, add the sandwich cookies and blend until they are fine crumbs. Add the melted butter and blend until the mixture is moist. Press the crust in the bottom of a 9-inch springform pan.
In the bowl of your electric mixer, beat the cream cheese until smooth. Beat in the sugar, melted dark chocolate, and cocoa powder. Beat in each egg one at a time. Beat in the vanilla extract until just combined. Don't over mix!
Pour the batter into the crust. Bake at 350° for 40-45 minutes or until center is almost set. Remove the cake from the oven and let it cool completely. Chill it overnight.