Lay a large piece of chocolate on a work surface. Place a towel against the end of the chocolate closest to you and push it against your hip. (The towel prevents the chocolate from getting all over you.) Hold a sharp knife, with one hand on each end, lengthwise across the chocolate and scrape the knife toward you over the chocolate. Alternatively, you can use a vegetable peeler on a smaller piece of chocolate. Three ounces of chocolate will produce about 2½ cups of shavings.