PREHEAT oven to 325°F Grease 1 1/2-quart baking dish. Chill small mixer bowl.
MELT butter in large saucepan. Remove from heat. Stir in flour. Gradually stir in evaporated milk and water. Cook over medium heat, stirring constantly, until mixture comes just to a boil. Stir in corn, chiles, egg yolks and 1/2 cup cheese. Beat egg whites in chilled mixer bowl until stiff peaks form. Fold into corn mixture. Pour into prepared baking dish.
BAKE for 50 to 55 minutes or until knife inserted near center comes out clean. Top with remaining cheese. Bake for additional 2 to 3 minutes or until cheese is melted.