In 2-quart saucepan, melt butter over medium heat. Stir in flour; cook 1 minute, stirring constantly, until bubbly. Stir in milk; cook 5 to 6 minutes, stirring constantly, until mixture thickens slightly. Stir in broth and remaining 1/2 teaspoon salt. Remove from heat; stir in cheese. Fold in macaroni.