Beans, vegetables, and water are the basic components of many of northern Italy's world-renowned soups. A long, gentle cooking time guarantees the melding of textures and flavors. Here we've used chicken broth as the liquid and added thin slices of prosciutto as a sophisticated accent just before serving. Make a pot of this on a cold winter's day, enjoy the aroma that will fill your house, and then eat. See for yourself how satisfying a bowlful of bean soup can be. A loaf of crusty bread, a piece of Asiago cheese, and good olive oil on the table are all you need as accompaniments.