Strew half the sugar on a work surface and place the pasta sfogliata on it. Strew the dough with the remaining sugar and press the sugar in with the heel of your hand. Roll out the dough, constantly sprinkling it with the sugar, on the work surface until it is a 12-inch square. Trim the edges of the dough and cut it into 4 strips, each 3 × 12 inches. Stack the 4 strips of dough together and press gently down the middle of the stack to make them adhere, as if forming the spine of an opened book, as in the illustration. Chill at least 1 hour.
Cut the stacked strips crosswise at ½-inch intervals to make 24 slices. One at a time, place the slices on the sugar-sprinkled work surface with the cut side down. Pinch each in the center, according to the illustration, and make a twist at the middle. Arrange the farfalle on cookie sheets lined with parchment, keeping them well apart from each other.
Bake the farfalle at 350 degrees for about 20 to 25 minutes, until they have expanded and caramelized well. Remove from the pan to a rack to cool.