Preheat the oven to 350°F (175°C) and lightly coat a 9x13-inch baking dish with non-stick spray or a touch of oil.

Bring a large pot of salted water to a rolling boil. Add the egg noodles and cook until al dente, following the instructions on the packaging. Drain thoroughly and set aside.

In a large skillet over medium heat, sauté the ground beef and chopped onion together until the meat is no longer pink and the onion is translucent. Carefully drain off any excess fat.

Stir in the minced garlic, salt, black pepper, Italian seasoning, tomato sauce, and drained diced tomatoes. Allow the mixture to simmer gently for approximately 5 to 7 minutes to deepen the flavors.

In a separate bowl, blend together the sour cream and cottage cheese until well combined. Add the cooked noodles to this creamy mixture and stir until evenly coated.

To assemble, layer half of the noodle and cream mixture into the prepared baking dish. Spoon half of the beef and tomato mixture over the noodles, then sprinkle with one cup of shredded cheddar cheese. Repeat the layering with the remaining noodles, beef mixture, and the final cup of cheese on top.

Place the dish in the oven and bake uncovered for 25 to 30 minutes, or until the cheese has melted and the edges are bubbling.

Allow the casserole to rest for 5 minutes after removing it from the oven. Slice and serve warm.