Preheat oven to 350°F and lightly grease a 9×13-inch baking dish with nonstick spray. Set aside.
In a mixing bowl, stir together chicken, condensed soup, mayonnaise, milk, onion, cheese, and frozen veggies. Gently fold in egg noodles and spread mixture into baking dish.
Sprinkle Panko bread crumbs evenly over the top, then drizzle with melted butter. Bake until golden brown and bubbly, about 30-35 minutes. Let sit 5 minutes before serving. Enjoy!
