Preheat the oven to 350°F (175°C).
In a large mixing bowl, combine the shredded chicken, cream of chicken soup, sour cream, chicken broth, mixed vegetables, garlic powder, onion powder, salt, and pepper. Stir until well combined.
In a separate bowl, prepare the stuffing mix according to package directions and mix in the melted butter.
Spread the chicken mixture evenly in the bottom of a greased 9x13 inch baking dish.
Top the chicken mixture with the prepared stuffing, spreading it evenly over the chicken.
Bake in the preheated oven for 45 minutes, or until the casserole is hot and bubbly, and the stuffing is golden brown.
Let it cool for a few minutes before serving.