Preheat your oven to 350°F.
Shred your cooked chicken into bite-sized pieces.
In a large mixing bowl, combine the shredded chicken, cream of chicken soup, sour cream, and shredded cheddar cheese. Add the frozen mixed vegetables, garlic powder, onion powder, salt, and pepper. Stir until well combined.
Transfer the mixture to a greased 9x13-inch baking dish and spread evenly.
Mix crushed Ritz crackers with melted butter and sprinkle evenly over the chicken mixture.
Bake for 25-30 minutes until bubbly and golden brown. Let cool for 5 minutes before serving.