In a skillet, cook beef with the diced onion until beef is fully cooked. Drain off and excess grease. Add garlic to the skillet and cook for 1 minute until fragrant.
Add the beef mixture to a large slow cooker along with the broth, beans, tomatoes, green chilies, chili powder and cumin. Stir to combine.
Cover and cook on low for up to 10 hours or high for 2 hours. Then add in the dried macaroni and cook on high for about 30 minutes until the pasta is tender. Stir in the cheese until melted and serve. Serves 6-8.