PREHEAT oven to 375° F. Grease 13 x 9-inch baking dish or disposable baking pan.
COMBINE cornstarch, salt and pepper in large saucepan. Stir in evaporated milk, water and butter. Cook over medium heat, stirring constantly, until mixture comes to a boil. Boil for 1 minute. Remove from heat. Stir in cheeses until melted. Place macaroni into prepared dish. Pour cheese sauce over macaroni; stir to coat. Sprinkle with paprika.
BAKE for 20 to 25 minutes or until bubbly.