Preheat your oven to 350°F (175°C).
Shred or dice the cooked chicken into bite-sized pieces and place in a large mixing bowl.
Prepare the stuffing mix according to the package instructions, using melted butter instead of water for extra flavor.
In the large mixing bowl with the chicken, add the cream of chicken soup, sour cream, chicken broth, garlic powder, onion powder, salt, and pepper. Mix until well combined, then fold in the frozen mixed vegetables and half of the shredded cheddar cheese.
Grease a 9x13 inch baking dish and spread the chicken mixture evenly across the bottom. Layer the prepared stuffing mix over the chicken mixture, then sprinkle the remaining shredded cheddar cheese on top. Bake for 30-35 minutes until bubbly and golden.
Let the casserole cool for 5-10 minutes before serving.