Stefano Callegari, a former pizzaiolo, has turned one bright idea into a small chain of fast-food shops with locations in Rome, Florence, and now New York. Working with pizza dough, Chef Callegari has devised a clever new sandwich format that’s ideal for juicy fillings. He calls his sandwiches trapizzini, and they have taken Italy by storm.

We talk to this pizza innovator about his now-famous trapizzini and his chain of Trapizzino restaurants.