Preheat your oven to 350°F (175°C) to ensure it's ready for baking.
In a large mixing bowl, thoroughly combine the shredded chicken, chicken broth, cream of mushroom soup, and frozen mixed vegetables. Add in the garlic powder, onion powder, dried thyme, and season with salt and pepper to your liking, mixing until everything is well incorporated.
Grease a 9x13 inch casserole dish with a little olive oil to prevent sticking, then spread the chicken mixture evenly across the bottom of the dish.
In a separate bowl, prepare the seasoned stuffing mix as directed on the package. This usually requires adding hot water or broth, allowing it to soak for a few minutes, and then fluffing it with a fork to achieve a light texture.
Carefully spoon the prepared stuffing mix over the chicken mixture in the casserole dish, spreading it evenly to cover all the chicken and veggies.
Drizzle a tablespoon of olive oil lightly over the stuffing to enhance its moisture and flavor while baking.
Cover the casserole dish tightly with aluminum foil to trap in steam, and place it in your preheated oven. Bake for 25 minutes.
After 25 minutes, carefully remove the foil and continue baking for another 20 minutes. This step will give the stuffing a chance to crisp up and achieve a lovely golden brown color on top.
Once the casserole is bubbling and the stuffing is beautifully golden, take it out of the oven and allow it to cool for about 5-10 minutes before serving. This will help the layers set a bit.
Just before serving, sprinkle chopped fresh parsley over the casserole for a bright and fresh touch.