Preheat your oven to 350ºF. This temperature is key to ensuring your casserole bakes evenly, becoming bubbly and golden on top.
Spray a 9×13-inch baking dish with cooking spray. This will prevent sticking and ensure that your Cheddar Chicken Spaghetti comes out perfectly every time.
Remove the meat from the rotisserie chicken, discarding the skin. Chop the chicken into bite-sized pieces and set aside. The rotisserie chicken will add incredible flavor and texture to your casserole.
Cook the spaghetti noodles according to the package directions for al dente. Drain the noodles and set aside. You want them perfectly cooked, as they will bake further in the oven.
In a large bowl, whisk together the chicken broth, cream of mushroom soup, cream of chicken soup, Worcestershire sauce, onion flakes, and garlic powder. This mixture will serve as the creamy base for your casserole.
Stir in 1 cup of shredded cheddar cheese into the soup mixture. This will melt beautifully while baking, creating that irresistible cheesy layer.
Layer the cooked spaghetti and chopped chicken in the prepared baking dish. Make sure to spread them out evenly for consistent flavor in every bite.
Pour the soup mixture over the noodles and chicken, ensuring everything is well-coated. This helps meld the flavors together, making each bite delightful.
Sprinkle the top of your casserole with the remaining cup of shredded cheddar cheese. This will create a nice cheesy crust as it bakes.
Bake uncovered for 30 to 40 minutes, until bubbly and golden. This is when the magic happens; your kitchen will fill with the most amazing aroma!