Set your oven to 350°F (175°C). Preheating ensures even cooking and helps the casserole bake to golden perfection. I always get this started before mixing so everything flows smoothly.
In a large bowl, add your cooked chicken, noodles, carrots, peas, and broccoli. Stir them together gently. This step makes sure the vegetables and protein are evenly spread before the creamy sauce is added.
In another bowl, whisk together the cream of chicken soup and milk until smooth. Season it with garlic powder, salt, and pepper. This mixture becomes the luscious binder that holds the casserole together.
Pour the sauce over your chicken and veggie mixture. Stir carefully so every noodle and vegetable gets coated. Transfer everything into your 9×13-inch baking dish, spreading it out evenly.
Sprinkle the shredded cheddar cheese across the top. If you’re using breadcrumbs, mix them with melted butter and scatter them over the cheese. This creates a golden, crunchy topping after baking.
Place the casserole in your preheated oven for about 30 minutes. You’ll know it’s ready when the cheese is bubbly and the topping is lightly browned. Let it cool for a few minutes before serving—it makes slicing easier.