Preheat oven to 350 deg f. Grease a 23 cm square pan. In a small bowl, combine flour, baking soda, and salt. Set aside. In a small sauce pan, combine sugar, butter and water. Bring to a boil. Remove from heat. Add 1 cup chocolate chips and the vanilla extract. Stir until chips are melted, and mixture is smooth. Transfer to a large mixer bowl. Add eggs, beating well after each addition. Stir in flour mixture and remaining chips. Spread in prepared pan. Bake for 35 minutes, just until center is set. Cool and cut into 6 cm squares. Makes 16 brownies.