Preheat your oven to 350°F.
Cook the spaghetti until al dente. Drain and set aside.
Heat olive oil in a large skillet over medium heat. Sauté the onion until soft and translucent, about 5-7 minutes. Add the garlic and cook for another minute.
Stir in the cream of chicken soup, cream of mushroom soup, chicken broth, fire-roasted tomatoes, sour cream, Seasoning Salt, garlic powder, onion powder, paprika, cayenne pepper (if using), and dried basil. Simmer for 5-7 minutes.
Remove the skillet from heat and stir in the shredded cheddar and pepper jack cheese until melted.
Combine the cooked spaghetti, shredded chicken, and the sauce.
Transfer to a greased 9x13-inch baking dish. Top with extra cheddar cheese.
Bake for 25-30 minutes, or until the top is golden and bubbly.
Garnish with fresh parsley and serve.