Brown Beef: Cook ground beef and onion in a large pot until browned and soft. Drain excess fat.
Add Broth: Pour in beef broth and bring to a boil.
Cook Macaroni: Stir in macaroni, cook for 7-8 minutes until al dente.
Add Cheese & Milk: Lower heat, stir in milk and cheddar, cook until melted and creamy.
Season & Serve: Add salt and pepper to taste, then serve hot.
