Preheat your oven to 350°F (175°C), and lightly grease a 9x13-inch baking dish.
In a large mixing bowl, combine the condensed chicken soup, Italian seasoning, sour cream, salt, and pepper. Stir until the ingredients are well blended.
Fold in the cooked and shredded chicken along with the sliced green onions into the mixture. Ensure the chicken is well coated with the creamy sauce.
Transfer the chicken mixture into the prepared 9x13-inch baking dish, spreading it out evenly.
In a separate bowl, combine the crushed Ritz crackers with the melted butter. Mix until the crackers are evenly coated with butter.
Sprinkle the buttered cracker crumbs evenly over the chicken mixture in the baking dish.
Place the casserole in the preheated oven and bake for 25-30 minutes, or until the topping is golden brown and the casserole is heated through.
Once baked, remove the casserole from the oven and let it cool slightly before serving. Enjoy!