Preheat the oven to 350°F (175°C) and lightly coat a 9×13-inch casserole dish with nonstick spray or a thin layer of oil.

In a wide skillet set over medium heat, warm the olive oil or butter until melted. Sauté the diced onion for approximately 3 to 4 minutes until translucent and soft. Stir in the minced garlic and cook briefly for about 30 seconds, just until aromatic.

Incorporate the uncooked rice into the skillet and stir for 1 to 2 minutes, allowing it to be well coated in the oil and aromatics. Pour in the chicken broth, add the salt, black pepper, and Italian seasoning. Stir to combine, bring to a light simmer, then turn off the heat.

Transfer the seasoned rice mixture into the greased baking dish, spreading it evenly. Distribute the raw chicken pieces uniformly over the rice layer.

In a mixing bowl, combine the cream cheese, cream of chicken soup, sour cream, and Parmesan. Whisk until the mixture becomes smooth and homogenous. Spoon and spread this sauce evenly over the chicken.

Cover the dish tightly with aluminum foil and place it in the preheated oven. Bake for 35 to 40 minutes until the chicken is cooked through and the rice has absorbed most of the liquid.

Remove the foil, scatter the shredded mozzarella across the top, and return the dish to the oven uncovered. Bake for an additional 5 to 7 minutes until the cheese is fully melted and lightly bubbling.

Let the casserole rest for 5 minutes after baking. Sprinkle with chopped fresh parsley if desired, and serve warm.