1. Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish.

2. In a large skillet over medium heat, cook the ground beef, onion, and garlic until the beef is browned and the onion is softened. Drain any excess fat.

3. Add the Italian seasoning, salt, and black pepper to the beef mixture, stirring well to incorporate the flavors.

4. Prepare the egg noodles according to the package instructions until they are al dente. Drain and set aside.

5. In a large bowl, combine the cooked beef mixture, cooked noodles, cream of mushroom soup, sour cream, diced tomatoes, and 1 cup of shredded cheddar cheese. Stir until everything is well mixed.

6. Transfer the mixture to the prepared baking dish. Sprinkle the remaining cheddar cheese and Parmesan cheese evenly over the top.

7. Bake the casserole uncovered for 25-30 minutes, or until the cheese is melted and bubbly.

8. Sprinkle the chopped parsley over the top, if desired. Allow the casserole to cool slightly before serving.