Slow cooker directions
1. Brown beef and onion in large skillet over medium heat 6 to 8 minutes, stirring to break up meat. Drain fat.
2. Place beef mixture, tomatoes, tomato sauce, chili powder, garlic salt, cumin, red pepper flakes, and black pepper in slow cooker; mix well. Cover; cook on low 4hours.
3. Cook macaroni according to package directions until al dente tender;drain. Add macaroni to slow cooker; mix well. Cover; cook on low 1 hour. Sprinkle with cheese; if desired.