Simmer chicken in water with onion, celery tops, carrot, salt and bay leaf until fork-tender, about 2½ to 3 hours. Cut meat from bones. Strain broth. Chill meat and broth separately.
In greased 1½-qt. casserole, arrange alternate layers of chicken, eggs and mushrooms by thirds.
Mix flour with ¼ c. broth until smooth. Heat remaining broth with cream; sti