Preheat your oven to 400°F (200°C).

In a medium mixing bowl, combine 1 cup of hot water with the stuffing mix, stirring gently. Let this mixture sit for about 5 minutes.

In a well-greased 9x13 inch baking dish, combine the cooked chopped chicken, sour cream, cream of chicken soup, and thawed mixed vegetables. Stir this mixture until all ingredients are combined.

Spread the prepared stuffing evenly over the top of the casserole mixture.

Place your assembled casserole in the preheated oven and bake for 25-30 minutes until the edges are bubbling and the top is golden brown.

Let the casserole rest for about 5-10 minutes before serving.