Cook pasta according to package instructions until al dente, drain, and set aside.
In a large skillet, brown the ground beef over medium-high heat until no longer pink. Drain excess fat.
Add diced onions and minced garlic to the skillet with the beef, cooking until onions are translucent.
Stir in salt, pepper, and Italian seasoning.
Pour in beef broth and tomato sauce, bringing the mixture to a simmer.
Lower the heat and stir in heavy cream, simmering until the sauce thickens.
Add cooked pasta shells to the skillet, stirring until they are evenly coated with the creamy sauce.
Remove from heat and stir in cheddar cheese until melted.
Garnish with chopped fresh parsley before serving.