01 - Preheat your oven to 375°F. Lightly grease a 9x13-inch baking dish with cooking spray or butter.
02 - Bring a large pot of salted water to a boil. Cook the ravioli according to package directions, usually 3–5 minutes. Drain well in a colander.
03 - In a large mixing bowl, combine the cooked ravioli, chicken, Alfredo sauce, milk, Italian seasoning, and black pepper. Mix gently to coat everything evenly without breaking the ravioli.
04 - Transfer the mixture to the prepared baking dish. Sprinkle mozzarella and Parmesan cheese evenly over the top.
05 - Cover the dish with aluminum foil and bake for 20 minutes.
06 - Remove the foil and bake for an additional 10–15 minutes, or until the cheese is golden and bubbly.
07 - Let the casserole cool for 5 minutes before garnishing with chopped parsley and serving hot.