Preheat the Oven: Preheat your oven to 350°F (175°C).
Cook the Beef: In a large skillet over medium heat, cook the ground beef, onion, and garlic until the beef is no longer pink and the onion is tender. Drain the excess fat.
Add Tomatoes and Seasoning: Stir in the diced tomatoes with their juice, tomato sauce, salt, pepper, oregano, and basil. Simmer for 10 minutes.
Cook the Noodles: Meanwhile, cook the egg noodles according to the package directions; drain and set aside.
Mix the Noodles and Sour Cream: In a large bowl, combine the cooked noodles and sour cream. Spread this mixture evenly in a greased 9x13 inch baking dish.
Assemble the Casserole: Top the noodle mixture with the beef mixture. Sprinkle with cheddar cheese, mozzarella cheese, and green onions.
Bake: Cover the baking dish with aluminum foil and bake in the preheated oven for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
Serve: Remove from the oven and let cool for a few minutes before serving.