Preheat oven to 350°F. Spray pan with vegetable pan spray. Melt 1 cup chocolate chips and butter together either in microwave oven or on top of range over low heat. Stir until chocolate is completely melted. Pour into electric mixer bowl. Add sugar; beat until well blended. Beat in eggs, one at time. Add vanilla. Stir in 1/2 cup flour, baking soda and salt; mix well. Add remaining flour and water; mix until smooth. Pour into prepared pan. Bake 40-45 minutes or until cake tests done. Place pan on cooling rack. Sprinkle remaining 1 cup chocolate chips over cake; let stand 2-3 minutes or until chips have softened. Gently spread melted chocolate over top of cake. Cool completely in pan before covering.