Preheat your oven to 350°F (175°C). Lightly grease a 9x13 casserole dish with olive oil or cooking spray and set it aside.

In a large pot, bring salted water to a boil. Cook the spaghetti for about 12 minutes until al dente. Reserve 1 cup of pasta water before draining and rinsing the spaghetti with cold water.

In a large mixing bowl, combine the cream of mushroom soup, cream of chicken soup, chicken broth, heavy cream, and sour cream. Stir until blended.

Season the mixture with garlic powder, onion powder, Italian seasoning, salt, and pepper. Add the chopped chicken and mix thoroughly.

Gently fold in the cooked spaghetti until coated in the creamy mixture. If it feels dry, add reserved pasta water.

Layer half of the chicken and pasta mixture into the prepared baking dish. Sprinkle 1 cup of mozzarella and ½ cup of cheddar cheese on top.

Pour the remaining chicken and pasta mixture over the cheese layer, then top with the rest of the mozzarella and cheddar.

Bake in the preheated oven for 35-45 minutes until the casserole is bubbling and the cheese is melted and golden.

Let it cool for about 5 minutes before serving. Garnish with fresh parsley.