Preheat your oven to 350°F (175°C) and grease a large casserole dish with cooking spray or butter.

In a skillet, heat oil and cook the chicken breasts for 6–7 minutes on each side until golden brown. Set aside to cool before shredding.

Boil salted water in a pot, add spaghetti and cook until al dente, about 8–10 minutes. Drain and toss with olive oil.

In a mixing bowl, combine shredded chicken, spaghetti, cream of chicken soup, bell peppers, and spices. Mix well.

Transfer the mixture to the casserole dish, evenly spread, and top with remaining cheddar cheese.

Bake in the oven for 25–30 minutes until cheese is bubbly and golden.

Let the casserole rest for about 5 minutes, then garnish with chopped green onions before serving.