Preheat the oven to 350°F (175°C) and grease a large casserole dish.

In a skillet, heat oil over medium heat. Cook chicken breasts for 6-7 minutes on each side until golden brown.

Boil salted water in a pot, add spaghetti, and cook until al dente, about 8-10 minutes. Drain and set aside.

In a mixing bowl, combine shredded chicken, cooked spaghetti, cream of chicken soup, bell peppers, paprika, cayenne pepper, garlic powder, and half of the cheddar cheese.

Transfer the mixture to the greased casserole dish and sprinkle remaining cheddar cheese on top.

Bake for 25-30 minutes until cheese is bubbly and golden brown.

Let the casserole rest for 5 minutes before serving. Garnish with sliced green onions.

Serve and enjoy your Spicy Southern Chicken Spaghetti Casserole!