In a large skillet, cook beef over medium heat 6-8 minutes or until no longer pink, breaking into crumbles; drain., Stir in macaroni, broth, milk, ketchup, steak seasoning, mustard and onion powder; bring to a boil. Reduce heat; simmer, uncovered, 10-15 minutes or until macaroni is tender. Stir in cheese until melted. Sprinkle with chives.