Preheat your oven to 350°F (175°C).
Grease a 9"x13" baking dish and set aside.
In a large mixing bowl, combine the melted salted butter, cream of chicken soup, sour cream, mayonnaise, ranch dressing seasoning, and optional salt, pepper, and minced garlic. Mix until well combined.
Add cheddar cheese, mozzarella cheese, and shredded chicken. Mix until well combined.
Transfer the mixture to the prepared baking dish and spread it out evenly.
In a separate bowl mix together the crushed Ritz crackers and melted unsalted butter until well combined.
Sprinkle the buttered cracker crumbs evenly over the top of the chicken mixture in the baking dish.
Bake in the preheated oven for 25-30 minutes or until the casserole is hot and bubbly and the top is golden brown.
Remove from the oven and let it cool for a few minutes before serving.
Garnish with chopped parsley and serve warm.