Creating the delicious Creamy Southern Spaghetti Bake is easy if you follow these simple steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) to prepare for baking.
2. Cook the Spaghetti: Cook the spaghetti according to package instructions until al dente. Drain and set aside.
3. Sauté the Meat: In a large skillet, heat olive oil over medium heat. Add ground beef or turkey and cook until browned, breaking it apart with a spoon.
4. Add Vegetables: Stir in diced onion and minced garlic, cooking until softened.
5. Combine Sauces: Add diced tomatoes, tomato paste, Italian seasoning, salt, and pepper to the meat mixture. Stir to combine and simmer for about 5 minutes.
6. Mix Creamy Sauce: In a separate bowl, mix softened cream cheese, sour cream, and half of the cheddar and mozzarella cheeses until smooth.
7. Combine Ingredients: In a large baking dish, combine cooked spaghetti with the meat sauce. Gently stir in the creamy sauce mixture until evenly distributed.
8. Add Cheese Topping: Sprinkle the remaining cheddar and mozzarella cheeses on top of the spaghetti mixture.
9. Bake: Place the dish in the preheated oven and bake for 30-35 minutes, or until the cheese is bubbly and golden.
10. Cool and Garnish: Remove from the oven and let it cool slightly. Garnish with chopped parsley, if desired.

By following these steps, you will create a creamy, cheesy, and utterly satisfying Southern spaghetti bake that everyone will love.