Preheat oven to 375°F. Grease a 9x13-inch baking dish with butter or non-stick spray.
Cook fettuccini according to package directions until al dente. Drain and set aside.
In a large bowl, whisk together cream of chicken soup, sour cream, chicken broth, Italian seasoning, and pepper until smooth.
Add softened cream cheese and whisk until creamy.
Stir in shredded chicken, half of the mozzarella and cheddar, and cooked fettuccini. Toss gently to coat.
Pour into prepared baking dish and top with remaining cheese.
Bake for 35 minutes, until cheese is melted and lightly browned.
Cool for 5 minutes before serving.