Creating the Irresistible Spicy Southern Chicken Spaghetti Casserole involves several straightforward steps:

1. Preheat your oven to 350°F (175°C).
2. Cook the Spaghetti: Boil the spaghetti according to package directions until al dente. Drain and set aside.
3. Sauté Vegetables: In a large skillet, heat olive oil over medium heat. Add the diced onions, bell peppers, and minced garlic. Sauté until the vegetables are tender.
4. Combine Ingredients: In a large mixing bowl, combine the cooked spaghetti, shredded chicken, sautéed vegetables, diced tomatoes, chicken broth, sour cream, Cajun seasoning, smoked paprika, and black pepper. Mix well until evenly combined.
5. Transfer Mixture: Pour the mixture into a greased 9×13-inch baking dish, spreading it out evenly.
6. Add Cheese: Top the casserole with shredded cheddar and mozzarella cheese.
7. Bake: Place the casserole in the preheated oven and bake for 30-35 minutes, or until the cheese is bubbly and golden brown.
8. Garnish: Remove from the oven and let it cool for a few minutes. Sprinkle with chopped parsley if desired.
9. Serve: Cut into squares and serve warm, ensuring each piece has plenty of cheese and filling.

Following these steps will result in a beautiful and delicious casserole that will become a staple in your cooking repertoire.