Preheat your oven to 375°F.
Cook the egg noodles in boiling water for about 7 minutes. Drain and set aside.
In a large bowl, mix the cream of chicken soup, milk, cheese, garlic powder, onion powder, salt, and pepper until combined.
Fold in the noodles, shredded chicken, and thawed vegetables. Pour the mixture into a greased 9x13-inch baking dish.
Crush the Ritz crackers, mix with melted butter, and sprinkle evenly over the top of the casserole.
Bake uncovered for 30 minutes until the top is golden and the casserole is bubbly.
Garnish with chopped green onions and serve warm.