Prep all ingredients by gathering cooked chicken, frozen mixed vegetables, and spices. Chop fresh vegetables if using.
If using raw chicken, boil or bake until fully cooked, about 20-30. Shred the chicken.
In a large bowl, combine shredded chicken, mixed vegetables, cream of chicken soup, chicken broth, garlic powder, onion powder, thyme, black pepper, and salt. Mix well.
Pour the chicken mixture into a greased 9x13 inch baking dish. In a separate bowl, whisk together milk and biscuit mix until just combined. Pour over the chicken mixture.
Preheat oven to 375°F. Bake for 30-35 until golden brown and bubbly. Let cool for 5-10 before serving.