Boil a pot of salted water and cook the elbow macaroni according to package instructions.
In a large skillet, brown the ground beef over medium heat until fully cooked.
Add the chopped onion and sauté until translucent.
Stir in the ketchup and mustard, mixing well.
Pour in the beef broth and milk, bringing the mixture to a gentle simmer.
Add the cooked macaroni to the skillet.
Gradually stir in the shredded cheddar cheese until melted.
Season with salt and pepper to taste.
Garnish with fresh parsley and serve hot.