In a large skillet, cook beef and onion over medium heat for 6-8 minutes or until beef is no longer pink, breaking up beef into crumbles; drain. Add garlic; cook 1-2 minutes longer. Stir in the ketchup, chiles, broth, chili sauce and seasonings. Bring to a boil. Reduce heat; simmer, uncovered, for 15 minutes, stirring occasionally.
Meanwhile, spread cut sides of buns with butter. Place on baking sheets, buttered side up. Broil 4 in. from the heat for 1-2 minutes or until toasted. Serve beef mixture in buns.