Creating Southern-Style Spicy Chicken Spaghetti Casserole is straightforward. Just follow these simple steps:

1. Preheat Oven: Begin by preheating your oven to 350°F (175°C).
2. Cook Spaghetti: In a large pot, cook spaghetti according to package instructions. Drain and set aside.
3. Prepare Chicken Mixture: In a large mixing bowl, combine the shredded chicken, cream of chicken soup, diced tomatoes (with juice), sour cream, garlic powder, onion powder, paprika, cayenne pepper, salt, and black pepper. Mix until well combined.
4. Combine Ingredients: Add the cooked spaghetti to the chicken mixture. If using, stir in the chopped bell peppers. Mix well to ensure everything is evenly coated.
5. Transfer to Baking Dish: Pour the mixture into a greased 9×13 inch baking dish, spreading it out evenly.
6. Top with Cheese: Sprinkle the shredded cheddar cheese evenly over the top of the casserole.
7. Bake: Place the casserole in the preheated oven. Bake for 30-35 minutes, or until the cheese is melted and bubbly.
8. Garnish: Once baked, remove from the oven and let it cool for a few minutes. Garnish with chopped green onions before serving.

These steps will guide you in creating this incredible casserole effortlessly.