01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish with cooking spray or butter.
02 - Cook egg noodles according to package instructions until al dente. Drain well and set aside.
03 - Heat a splash of oil in a large skillet over medium heat. Sauté onion, carrots, celery, and garlic for 4–5 minutes until softened.
04 - In a large bowl, combine cooked vegetables, chicken, peas, cream of chicken soup, sour cream, milk, cheddar cheese, thyme, salt, and pepper. Add cooked noodles and toss gently until evenly coated.
05 - Spread the mixture evenly in the prepared baking dish.
06 - In a separate bowl, mix panko breadcrumbs, Parmesan cheese, melted butter, and parsley until combined.
07 - Sprinkle the crumble topping evenly over the casserole. Bake uncovered for 30–35 minutes until golden and bubbling.
08 - Let the casserole rest for 5–10 minutes before serving to allow the filling to set.