Making Creamy Southern Spaghetti Bake is a straightforward process that yields delightful results. Follow these steps for success:

1. Preheat your oven to 350°F (175°C).
2. Cook the Spaghetti: Boil water in a large pot, add salt, and cook the spaghetti according to package instructions until al dente. Drain and set aside.
3. Cook the Meat: In a large skillet, heat olive oil over medium heat. Add ground beef or sausage, and cook until browned. Drain excess fat.
4. Add Vegetables: Stir in diced onion and minced garlic; cook for an additional 3-4 minutes until the onion is translucent.
5. Mix Ingredients: In the skillet, combine the cooked meat mixture with diced tomatoes, cream of mushroom soup, sour cream, Italian seasoning, and salt and pepper. Stir until well combined.
6. Combine with Spaghetti: In a large bowl, combine the meat mixture with the drained spaghetti. Mix thoroughly to ensure even distribution.
7. Transfer to Baking Dish: Pour the spaghetti mixture into a greased 9×13-inch baking dish. Spread it evenly.
8. Add Cheese: Top the spaghetti mixture with shredded cheddar cheese and mozzarella cheese.
9. Bake: Place the baking dish in the preheated oven and bake for 30-35 minutes or until the cheese is melted and bubbly.
10. Garnish and Serve: Once baked, remove from the oven and sprinkle with fresh parsley or basil before serving.

By following these straightforward instructions, you’ll create a creamy, delightful pasta bake that everyone will love.