Heat oven to 325F. Grease 9 inch square baking pan. In medium saucepan over low heat cook sugar, butter and water, stirring constantly until mixture comes to the boil. Remove from heat; immediately add one cup of chocolate chips stirring until chips are melted. Stir in eggs and vanilla until blended . Combine flour baking soda and salt; stir into chocolate mixture. Stir in remaining one cup of chips and nuts if desired. Pour into prepared pan. Bake 20 to 25 minutes or until brownies begin to pull away from sides of pan. Cool completely. Cut into bars. (About 18 brownies)