In a saucepan over medium heat, cook zucchini in water and salt until just tender, about 6 minutes. Add corn; cook for 1 minutes. Drain. Stir in chilies; pour into a greased 1-1/2 quart shallow baking dish. Melt butter in a saucepan; stir in flour and seasonings until smooth and bubbly. Stir in milk; bring to a boil, stirring constantly. Boil 3-4 minutes or until thickened. Remove from heat and stir in cheese until melted. Pour over vegetables. Bake, uncovered, at 350 for 20 minutes or until bubbly. Makes 6 servings.