Cook the pasta shells according to package directions until al dente. Drain and set aside.
In a large skillet over medium heat, heat olive oil. Add ground beef and cook until browned, breaking it up as it cooks.
Add diced onion and cook until translucent, about 3-4 minutes. Stir in garlic and cook for another 30 seconds.
Season with Italian seasoning, paprika, mustard powder, salt, and pepper.
Sprinkle flour over the beef mixture and stir well to combine.
Gradually pour in the beef broth and tomato sauce, stirring until well blended. Let simmer for 5-6 minutes until slightly thickened.
Lower the heat and stir in heavy cream and shredded cheddar cheese until smooth and creamy.
Add the cooked pasta shells and toss to coat evenly.
Serve hot, garnished with fresh parsley.