To learn more, read the article: Mix the dough: Sift together the flour, cinnaamon, ginger, nutmeg, salt, baking soda, allspice, and pepper. In the bowl of a stand mixer fitted with the paddle attachment, cream the butter on medium-low speed until smooth, about 2 min. Add the brown sugar in three additions and then add the molasses; scrape the bowl as needed. Mix for another 2 min. Blend in the egg yolk, egg, and vanilla, scraping the bowl again. Reduce the speed to low and add the dry ingredients in three additions, mixing just until combined. Portion the dough into thirds, wrap each third in plastic, and refrigerate until slightly firm, about 30 min. Shape the dough: Have ready three 15-inch sheets of plastic wrap. Whisk the egg white lightly with 1 teaspoon water. Put the chopped walnuts in a long, shallow pan (like a 7x11-inch Pyrex dish). Working with one piece of dough at a time on a lightly floured surface, roll into a log about 8 inches long. Set it on a sheet of waxed paper. Brush lightly all over with the egg white and then roll the log in the walnuts, pressing gently so the nuts adhere. The roll should lengthen to at least 9 inches. Position the log on a sheet of plastic wrap, centering it at the long edge closest to you. Roll tightly, twisting the ends firmly to seal. With your hands on either end of the log, push firmly toward the center to compact the dough. The finished log should measure about 9 inches long and 1-3/4 inches thick. Repeat with the remaining dough. Refrigerate until firm enough to slice, at least 2 hours, or freeze for up to three months. Bake the cookies: Position racks in the upper and lower thirds of the oven. Heat the oven to 350°F. Line two rimmed baking sheets with parchment. Working with one log at a time, use a tomato knife or other small serrated knife to slice the dough into 1/4-inch rounds, using a gentle sawing motion. Set the rounds 1 inch apart on the prepared pans and bake until the tops feel set and slightly firm, about 14 minutes, rotating the pans as needed. Let cool on the pans for 5 minutes. With a thin metal spatula, transfer the cookies to racks. When cool, store between sheets of waxed paper in a tightly covered container for up to a week, or freeze for up to three months.