Preheat your oven to 375°F (190°C).
In a large mixing bowl, combine the shredded chicken, frozen mixed vegetables, cream of chicken soup, milk, garlic powder, onion powder, thyme, black pepper, and salt. Mix well until all ingredients are combined.
Pour the chicken mixture into a greased 9x13-inch baking dish, spreading it evenly.
Unroll the crescent roll dough and lay it over the top of the chicken mixture, pressing the seams together to seal.
Bake in the preheated oven for 25-30 minutes, or until the crescent dough is golden brown and the filling is bubbly.
Remove from the oven and sprinkle the shredded cheddar cheese on top. Return to the oven for an additional 5 minutes, or until the cheese is melted.
Let it cool for a few minutes before serving.