01 - Set oven to 400°F (204°C) and grease a 2-quart baking dish.
02 - Combine shredded chicken, mixed vegetables, cream of chicken soup, 1/2 cup milk, garlic powder, onion powder, black pepper, and salt in a large mixing bowl. Stir thoroughly until evenly mixed.
03 - Spread chicken mixture evenly in the prepared baking dish.
04 - In a medium bowl, whisk together flour, baking powder, and salt. Cut in the cold cubed butter until mixture forms coarse crumbs. Add 1/2 cup whole milk and stir just until a soft dough forms.
05 - Spoon tablespoonfuls of biscuit dough evenly over the chicken filling, leaving small gaps for steam to escape.
06 - Bake on the center rack for 25-30 minutes, or until biscuits are golden brown and filling is bubbling.
07 - Allow to cool for 5-10 minutes before serving warm.