Mix 1/3 cup soft butter with 1/3 cup flour. Add 1/2 teaspoon celery salt and 1/4 teaspoon pepper. Add 2 cups milk and mix well. Cook until slightly thickened (like white sauce) then add 2 cups cubed cooked chicken and 1 can creamed corn. Place in casserole dish. Cover with cracker crumbs. Bake at 350 degrees for 30-40 minutes.