Chocolate-Vanilla Swirl Cookies

"The first word that came to mind when I saw these intricately swirled cookies was Rorschach: every one expresses something different, just like the famous inkblot test. The recipe is from my talented dear friend Nora Tong, owner of Nora's Patisserie in Daly City, California, about six miles south of San Francisco. She uses a special method of stretching and twisting the dough into two-tone logs, so that when the cookies are sliced, each is a unique work of art. For seasonal variations, customize the sugar coating on the outside of the logs, from red and green for Christmastime to spooky black and orange for Halloween. I always have one or two of these dough logs on hand in my refrigerator or freezer so I can slice and bake on demand. This recipe exemplifies how weighing ingredients is more accurate than measuring by volume. For example, if you measure different brands of cocoa powder in a cup measure and then put them on a scale, you will discover they weigh differently. But if you use weight as your measuring method, you will always end up with the same amount of each ingredient and your cookies will always have the optimum amount of chocolate flavor...."