Follow these simple steps for a perfect Chicken Noodle Casserole every time:

1. Preheat Oven & Prepare Dish: Preheat your oven to 375°F (190°C). Generously grease a 9×13 inch baking dish with butter or non-stick cooking spray. This prevents sticking and makes cleanup easier.
2. Cook the Noodles: Bring a large pot of salted water to a rolling boil. Add the egg noodles and cook according to package directions, but aim for the lower end of the time range – you want them slightly al dente (firm to the bite). They will continue to cook in the oven, and overcooking them now will result in mushy noodles later. Drain the noodles well and set them aside. Rinsing briefly under cold water can stop the cooking process if needed.
3. Sauté Aromatics: While the noodles are cooking, melt 2 tablespoons of the butter in a medium skillet over medium heat. Add the chopped onion and celery. Sauté for 5-7 minutes, stirring occasionally, until the vegetables are softened and the onion is translucent. This step builds a crucial flavor base for the casserole. Avoid browning them too much.
4. Combine Sauce Ingredients: In a large mixing bowl, whisk together the condensed cream of chicken soup, condensed cream of mushroom soup, and milk until smooth. Stir in the salt, black pepper, garlic powder (if using), and onion powder (if using). Taste the sauce base at this point and adjust seasonings if necessary, keeping in mind the saltiness of your chicken and the Parmesan in the topping.
5. Mix the Casserole: To the large bowl with the sauce, add the cooked and drained egg noodles, the shredded or cubed cooked chicken, the sautéed onion and celery mixture, and the frozen peas and carrots. Gently stir everything together until the noodles, chicken, and vegetables are evenly coated with the creamy sauce. Be careful not to break the noodles too much.
6. Transfer to Baking Dish: Pour the chicken noodle mixture into the prepared 9×13 inch baking dish. Spread it out evenly using a spatula or the back of a spoon. Ensure the ingredients are distributed well for consistent baking.
7. Prepare the Topping: In a small bowl, melt the remaining 2 tablespoons of butter in the microwave (or in the same skillet used earlier, wiped clean). Add the Panko breadcrumbs and the grated Parmesan cheese (if using) to the melted butter. Stir well until the breadcrumbs are evenly coated. This mixture will create that delightful golden, crunchy crust.
8. Top the Casserole: Sprinkle the Panko-Parmesan mixture evenly over the top of the casserole in the baking dish. Ensure full coverage for maximum crunch in every bite.
9. Bake to Perfection: Place the baking dish in the preheated oven. Bake for 25-30 minutes, or until the casserole is hot, bubbly around the edges, and the Panko topping is beautifully golden brown and crisp. If the topping starts browning too quickly before the casserole is heated through, you can loosely tent the dish with aluminum foil for the remaining baking time.
10. Rest Before Serving: Once baked, carefully remove the casserole from the oven. Let it rest for 5-10 minutes before serving. This allows the sauce to thicken slightly and makes it easier to serve without being too runny. It also prevents burnt tongues!