Preheat oven to 350°F and lightly grease a 9x13-inch casserole dish.
In a large mixing bowl, combine the cream of chicken soup, sour cream, milk, garlic powder, onion powder, salt, and pepper. Mix well.
Stir in shredded rotisserie chicken and 1 1/2 cups of cheddar cheese.
Transfer the mixture to the prepared casserole dish and spread evenly.
Top with remaining 1/2 cup of cheddar cheese.
In a small bowl, combine crushed Ritz crackers with melted butter and sprinkle evenly over the casserole.
Bake uncovered for 30-35 minutes, or until hot and bubbly with a golden top.
Let rest for 5 minutes before serving.