Heat oven to 425. Coat an 8 x 3 cake pan with nonstick spray. Line bottom with wax paper. spray paper. Have a larger roasting pan ready. Melt chips and butter together. Stir until well blended. Beat eggs in a large bowl with mixer on high for seven minutes or until tripled and soft peaks form. Fold in chocolate mixture until well blended. Pour into cake pan. Place large pan in oven. place cake pan inside. Pour boiling water into roasting pan to come halfway up sides of cake pan. Cover cake pan loosely with foil bake 40 minutes. ( cake looks soft but sets when cold.) Cool cake in pan on wire rack. Cover and refrigerate 3 hours or until firm. Invert on to serving platter. shake down sharply to release cake. Peel off paper. if desired. lay five 3/4 inch strips of paper 3/4 inch apart on cake. sift cocoa between strips ; carefully lift paper. Repeat in opposite direction. this time sifting on confectioners sugar.