In a small bowl, combine the wafer crumbs, confectioners? sugar and cocoa; stir in the butter. Press onto the bottom of a greased 9-inch springform pan; set aside. In a large bowl, beat cream cheese and butter until smooth. Beat in milk and vanilla. Beat in cocoa until well blended. Add eggs; beat on low just until combined. Fold in brownies. Spoon into crust. Place pan on a baking sheet. Bake at 350° for 50-55 minutes or until center is almost set. Cool on a wire rack for 10 minutes. Carefully run a knife around the edge of pan to loosen. Cool 1 hour longer. Refrigerate overnight. Remove sides of pan. Garnish with whipped topping and pecans if desired. Refrigerate leftovers.