Peel the broccoli stems. In a pot wide enough to hold the whole broccoli heads, bring the water, bay leaves, butter and salt to a boil. Add the broccoli and cover. Cook over moderate heat, turning once, until tender, 15 minutes. Transfer the broccoli to a warmed platter and cover with foil. Boil the cooking liquid until reduced to 1/4 cup, 5 minutes. Pour the liquid over the broccoli, discard the bay leaves and serve.