Meanwhile, melt remaining 2 tablespoons butter in 4-quart saucepan over low heat. Stir in flour and salt. Cook 1 minute, stirring with whisk. While continuing to stir, add milk. Cook and stir 1 to 2 minutes or until thickened and smooth. Stir in frozen broccoli and Cheddar cheese. Cover; cook 8 to 10 minutes, stirring occasionally, until thoroughly heated. Remove form heat; stir in macaroni until well blended.