Preheat the oven to 350°F (175°C) and grease a 9x13-inch baking dish with olive oil or butter.

In a large skillet over medium heat, melt the olive oil or unsalted butter, then add diced onion and sauté for 3–4 minutes until soft. Add minced garlic and stir for 30 seconds.

Stir in uncooked long-grain white rice, then pour in chicken broth, salt, pepper, and Italian seasoning. Let it come to a gentle simmer before turning off the heat.

Transfer the rice mixture to the greased baking dish and spread evenly. Arrange the chicken pieces over the rice in a single layer.

In a separate bowl, whisk cream of chicken soup, softened cream cheese, sour cream, and grated Parmesan until smooth. Spread this over the chicken in the casserole.

Cover the baking dish tightly with foil and bake for 35–40 minutes, until the rice is tender and the chicken is fully cooked.

Remove the foil and sprinkle shredded mozzarella cheese on top, then return to the oven uncovered for 5–7 minutes until cheese is melted and bubbly.

Let the casserole rest for 5 minutes before serving. Garnish with chopped parsley if desired.