Preheat oven to 350°F. Spray baking 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. Fold remaining cup of chocolate chips into batter. Pour into prepared pan.
Refer to baking chart in techniques section for baking times and temperatures for specific pans.
Cool 10 minutes in pan on rack; remove and cool completely before decorating.
Makes about 6 cups batter.