In a large skillet over medium heat, brown the ground beef until fully cooked, about 5-7 minutes. Drain excess fat if necessary.

Add the diced onion and minced garlic to the skillet. Sauté until the onion is translucent, about 3-4 minutes.

Stir in the salt, black pepper, and Italian seasoning.

Pour in the beef broth and bring to a simmer. Add the heavy cream and stir to combine.

In a separate pot, cook the pasta shells according to package instructions until al dente. Drain and set aside.

Once the sauce is simmering, add the cooked pasta shells to the skillet and stir until well coated.

Mix in the cheddar cheese and half of the Parmesan cheese until melted and creamy.

Serve hot, garnished with the remaining Parmesan cheese and chopped parsley.