There are many different variations of this filling soup, but the main ingredients are meatballs and greens like escaroles, endives, spinach, or kale. Traditionally, the recipe calls for the soup being cooked for over three days. On the first day, fresh chicken stock is prepared, on the second day the meatballs are made from scratch and on the third day all the ingredients of the soup are added to the simmering pot of chicken stock.