Preheat your oven to 350°F (175°C).

In a large pot, boil salted water and cook the jumbo pasta shells according to the package directions until al dente. Drain and set aside.

In a large skillet, brown the ground beef over medium heat. Add the chopped onion and minced garlic. Sauté until the onion becomes translucent and the beef is thoroughly cooked. Drain any excess grease.

In a large bowl, combine the cream of mushroom soup, sour cream, Italian seasoning, salt, and pepper. Stir in half of the cheddar cheese.

Add the cooked beef mixture to the creamy sauce and mix well. Gently fold in the cooked pasta shells, ensuring they are well coated.

Spread the mixture evenly in a greased casserole dish. Top with the remaining cheddar cheese.

Place the dish in the preheated oven and bake for 20 minutes, or until the cheese is bubbly and golden.

Remove from the oven and garnish with fresh parsley before serving.