Emma Belforte, in a recipe described in La cucina livornese, recommends cooking the white beans and greens for three (!) hours, and then serving them with couscous for a full meal. I have cut the cooking time in half. For a fuller flavor, use broth instead of water. While most versions of this recipe ignore garlic, you would not be remiss in adding some. A Roman version includes lettuce and omits the onions. It is called fagioli con la lattuga.