Brown ground beef in a large skillet over medium-high heat. Drain off any excess fat.
Add macaroni, beef broth, and milk to the skillet. Bring to a boil, then reduce heat and simmer for 15-20 minutes, or until macaroni is cooked through.
Stir in cheddar cheese until melted. Serve immediately.
Notes
For extra flavor, add a teaspoon of Worcestershire sauce or a tablespoon of tomato paste to the ground beef while it's browning.