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

Prepare the spaghetti by bringing a large pot of salted water to boil. Cook the spaghetti for about 12 minutes, or until al dente, then drain and rinse with cold water to prevent sticking. Reserve 1 cup of the pasta water.

In a large bowl, combine the cream of mushroom soup, cream of chicken soup, chicken broth, heavy cream, and sour cream. Mix well.

Stir in the garlic powder, onion powder, Italian seasoning, salt, and black pepper. Add the chopped chicken and mix until everything is well-combined.

Fold the cooked spaghetti into the creamy mixture, ensuring that all the pasta is evenly coated. Adjust the consistency with the reserved pasta water if it feels too thick.

Transfer half of the pasta mixture into the prepared dish and sprinkle with 1 cup of mozzarella and ½ cup of cheddar cheese. Layer the remaining pasta mixture on top, followed by the rest of the cheese.

Bake in the preheated oven for 35-45 minutes, or until the cheese is melted and bubbly.

Allow the casserole to sit for about 5 minutes, garnish with fresh parsley, and serve.