Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius) and lightly grease a 9x13 inch baking dish.
In a large mixing bowl, whisk together the condensed cream of chicken soup, sour cream, chicken broth, black pepper, and garlic powder until smooth.
Fold the shredded chicken and frozen vegetables into the cream mixture until thoroughly combined.
Spread the chicken mixture evenly into the bottom of the prepared baking dish.
Sprinkle the dry stuffing mix evenly over the top of the chicken layer.
Drizzle the melted butter uniformly over the stuffing to ensure even browning.
Bake for 30 to 35 minutes, or until the casserole is bubbling and the stuffing top is golden brown.
Remove from the oven and allow to rest for 5 minutes before serving.