In a small bowl, combine cookie crumbs and sugar; stir in butter. Press onto the bottom and 1 ½ inches up the sides of a greased 9-inch spring form pan Bake at 350 for 10 minutes. Cool on a wire rack. Reduce heat to 325.
In a saucepan over low heat, melt chocolate chips; stir until smooth. Remove from the heat; add cream and mix well; set aside. In a mixing bowl, beat cream cheese and sugar until smooth. Add cocoa and beat well. Add eggs; beat on low just until combined. Stir in vanilla and reserved chocolate mixture just until blended. Pour over crust. Then bake for 45-50 minutes or until center is almost set.
For topping, melt chocolate chips in a saucepan over low heat, stirring until smooth. Remove from the heat. Stir in cream and vanilla; mix well. Spread over filling. Refrigerate overnight. Carefully run a knife around the edge of the pan to loosen. Remove the sides of the pan.