In a large bowl combine cream of chicken soup, mayonnaise, and milk. Add in celery and diced onion. Fold in the tuna, cooked egg noodles and ¼ cup of shredded cheddar cheese. Season with salt and pepper to taste.
Place into a 9×13 inch baking dish. Place into the oven and bake for 40 minutes. After about 30 minutes remove from the oven and top with the remaining shredded cheddar cheese and crushed chips.
Return to the oven and finish baking until the cheese has melted.