Bring a large pot of salted water to a rolling boil. Add the egg noodles and cook according to package directions until al dente, about 7-9 minutes. Drain and set aside.

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

Sprinkle in Italian seasoning, salt, and pepper. Stir well. Pour in diced tomatoes and let simmer for 2-3 minutes. Remove from heat.

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

Preheat oven to 350°F (175°C). Grease a 9x13-inch baking dish. Layer half of the cooked noodles, half of the meat mixture, and half of the sauce. Repeat layers.

Sprinkle Parmesan cheese over the final layer. Cover with aluminum foil and bake for 20 minutes, then remove foil and bake for an additional 10-15 minutes until cheese is melted and bubbly.

Allow to rest for 5 minutes. Garnish with fresh parsley if desired before serving.