Preheat your oven to 350°F. Shred the cooked chicken and prepare the other ingredients.
In a large mixing bowl, combine shredded chicken, sour cream, cream of chicken soup, garlic powder, onion powder, black pepper, and salt. Mix well.
Fold in half of the shredded cheddar cheese and green onions, if using. Spread the mixture into a greased 9x13-inch baking dish.
In a separate bowl, mix crushed Ritz crackers with melted butter. Sprinkle over the chicken mixture and top with remaining cheddar cheese.
Bake for 30-35 minutes until bubbly and golden brown. Let cool for 5-10 minutes before serving.