Preheat your oven to 375 degrees F. Lightly grease a 9×13 inch baking dish.
Cook egg noodles according to package directions until al dente. Drain well.
In a large bowl, combine the cream of chicken soup, cream of mushroom soup, sour cream, milk, onion powder, and pepper. Mix until smooth.
Stir in the shredded chicken, drained noodles, and 1 1/2 cups of the shredded cheddar cheese into the soup mixture. Mix gently to coat everything evenly.
Pour the mixture into the prepared baking dish.
In a small bowl, combine the crushed crackers and melted butter. Sprinkle this mixture evenly over the top of the casserole.
Bake for 25 minutes.
Remove from the oven and sprinkle the remaining 1/2 cup of cheddar cheese over the top. Bake for another 5 minutes, or until the cheese is melted and bubbly and the topping is golden brown.
Let the casserole rest for 5 minutes before serving.
Notes
You can substitute cream of celery soup for the cream of mushroom soup if you prefer.
For a make-ahead option, assemble the casserole completely, cover it, and refrigerate for up to 24 hours. Add 10-15 minutes to the initial baking time if baking straight from the refrigerator.
Use leftover cooked chicken or quickly cook chicken breasts to shred if you do not have rotisserie chicken.