Preheat oven to 350F degrees. Spray 9 x 13 baking dish with non-stick cooking spray.
In a large bowl, combine chicken, cream of chicken soup, mayonnaise, milk, diced onion, shredded cheese and frozen peas and carrots. Stir until combined.
Gently stir in cooked egg noodles. Pour in baking dish.
Bake uncovered for about 30-35 minutes until bubbly and top is golden brown. Garnish with fresh parsley.