Preheat the oven to 375°F (190°C).
In a large bowl, combine shredded chicken, mixed vegetables, cream of chicken soup, milk, garlic powder, onion powder, and black pepper.
Transfer the mixture into a greased 9x13 inch baking dish.
Open the biscuit dough and evenly place the biscuits on top of the chicken mixture.
Bake in the preheated oven for 25-30 minutes or until the biscuits are golden brown.
Remove from the oven and sprinkle with chopped parsley, if using.
Serve warm and enjoy your Chicken Biscuit Casserole!