Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with cooking spray or a little olive oil.

In a large pot, boil the diced potatoes in salted water until tender, about 10-12 minutes. Drain and set aside.

In a large mixing bowl, combine the shredded chicken, broccoli, carrots, green peas, cooked potatoes, garlic powder, onion powder, salt, black pepper, paprika, and cayenne pepper (if using).

In a separate bowl, whisk together the milk and sour cream until smooth. Pour this mixture over the chicken and veggie mixture, stirring until everything is well combined.

Transfer the mixture to the prepared baking dish, spreading it evenly. Top with shredded cheddar cheese.

Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 15-20 minutes, or until the cheese is bubbly and golden brown.

Once done, remove from the oven and let it cool for 5 minutes. Garnish with chopped parsley before serving.