Preheat the oven to 375°F (190°C) and lightly grease a 9x13-inch baking dish.
In a large bowl, mix the rotisserie chicken, frozen vegetables, cream of chicken soup, sour cream, shredded cheddar cheese, chicken broth, garlic powder, onion powder, salt, and pepper until well combined.
Spread the creamy chicken mixture evenly into the prepared baking dish.
In a medium bowl, gently stir together the Cheddar Bay Biscuit mix and water until just combined.
Drop spoonfuls of the biscuit batter over the chicken filling and sprinkle with extra cheddar cheese if desired.
Brush or drizzle the melted butter mixed with the seasoning packet over the biscuit topping.
Bake for 30–35 minutes until the biscuit topping is golden and the filling is bubbling. Rest 5 minutes before serving.