Bring a large pot of salted water to a boil. Cook the spaghetti until al dente according to package instructions. Drain and toss with butter to prevent sticking. Set aside.

Heat olive oil in a large skillet over medium heat. Add the diced onion and green bell pepper. Cook until softened, about 4-5 minutes. Add the minced garlic and cook for another minute.

Stir in the cream of chicken soup, cream of mushroom soup, diced tomatoes with green chilies, chicken broth, garlic powder, onion powder, paprika (if using), Italian seasoning, salt, and black pepper. Simmer for 5-7 minutes, stirring occasionally, until the sauce is smooth and well combined.

In a large mixing bowl, combine the cooked spaghetti, shredded chicken, half of the cheddar cheese, and the sauce. Mix until everything is evenly coated.

Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish.

Pour the spaghetti mixture into the prepared dish and spread it out evenly.

Sprinkle the remaining cheddar cheese, mozzarella cheese, and Parmesan cheese evenly over the top.

Cover the dish with foil and bake for 20 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.

Let the casserole rest for 5 minutes. Garnish with fresh parsley before serving.