Preheat your oven to 375°F (190°C).
In a large mixing bowl, combine cooked chicken, frozen mixed vegetables, cream of chicken soup, garlic powder, onion powder, salt, pepper, and chicken broth. Mix thoroughly.
Transfer the filling into a casserole or pie dish and spread evenly.
In another bowl, whisk together flour, baking powder, and salt. Cut in cold butter until it resembles coarse crumbs. Stir in cheddar cheese and garlic powder, then gradually mix in milk until just combined.
Drop spoonfuls of the biscuit dough over the chicken filling, covering it as evenly as possible.
Bake in the preheated oven for about 30 minutes, until the topping is golden brown and the filling is bubbling.
Allow the pot pie to cool for a few minutes before serving.