Preheat oven to 350F.

Separate celery into stalks, remove leaves (save for another purpose, like making more vegetable broth), and trim.  Wash well, and cut into pieces about 3/4" thick.  Place celery in an ungreased casserole dish.

Dice bacon with kitchen scissors; add bacon and sliced onion to casserole, atop the celery.  Sprinkle all with fresh parsley.  Pour broth over dish; don't stir.  Dot casserole with small bits of butter.

Cover dish and bake for 30-45 minutes, or until celery is cooked but not mushy.