Begin by bringing a large pot of salted water to a rolling boil. Add the egg noodles and cook for about 7-9 minutes, or until they reach al dente. Once cooked, drain the noodles in a colander and set them aside to cool slightly.

In a large skillet, heat olive oil over medium heat. Add ground beef, diced onion, and minced garlic; cook for 6-8 minutes until browned. Drain excess fat.

With the meat mixture still in the skillet, sprinkle in Italian seasoning, salt, and pepper. Stir in diced tomatoes and cook for 2-3 minutes until heated through. Remove from heat.

In a medium bowl, whisk together cream of mushroom soup and sour cream until smooth. Set aside.

Preheat your oven to 350°F (175°C).

In a greased 9x13-inch baking dish, layer half of the cooked egg noodles, half of the meat mixture, and half of the creamy sauce. Repeat layers, finishing with remaining meat mix and sauce. Sprinkle with Parmesan cheese.

Cover the dish with aluminum foil and bake for 20 minutes to meld flavors.

Remove the foil and continue baking for another 10-15 minutes until the cheese is melted and golden.

Allow the casserole to cool for 5-10 minutes before serving. Garnish with fresh parsley if desired.