• Chop the chocolate into small pieces, about 1/8-1/4 inch in size. The small size is required so that you can more easily slice the cookie dough. When you have chopped the chocolate, sift the chocolate with a medium-coarse strainer to remove the tiny pieces. You should be left with small chunks and about 3-1/2 ounces of chocolate.
• The finer pieces are sifted out, because if they are added to the cookie dough, they will turn the dough dark.
• Place the sugar in the bowl of a stand mixer. Zest the orange on top of the sugar until you have about 2 teaspoons. Use your fingers to rub the zest into the sugar. Add the kosher salt and the butter. With the paddle attachment beat the sugar, salt and butter on medium speed until it is well combined and looks creamy, 2 minutes.
• Add the flour and mix on medium-low speed just until the dough starts to come together and forms large clumps. Add the chopped chocolate and mix on low until the chocolate is dispersed throughout the dough. The dough will still be large clumps.
• Turn out the dough onto a clean, lightly floured surface. Gently gather the dough together into a disk by gently pressing the dough together and shaping it into a round disk. The dough should weigh about 940 grams. Once you have a round disk shape, use a knife or a bench knife to cut directly in half and set aside.
• Clean your work surface with a bench scraper. Shape each dough half into a 7-inch long, 1-1/2 diameter log, by forming it into a short cylinder and then rolling it back and form with open hands. Move your hands from the center to the outside edges and back again to maintain even thickness.
• Wrap the parchment paper around your dough log, lengthwise. Then twist each end of the paper into pigtails in opposite directions (one towards you and one away from you) to form a locking mechanism. With each twist, the dough will compress and becomes smoothed out (think of it like a sausage in a casing). Roll from the center outward until you feel that you have a smooth, cylindrical log.
• Chill the dough for at least 1 hours and up to 2 days.

Baking the Cookies

• Preheat the oven to 325F degrees. Remove one of the logs of cookie dough from the refrigerator and let it sit at room temperature for 10 minutes. Pour 1/2 cup of demerara sugar on a piece of parchment paper at least 10-inches long. Brush the dough with egg white and then roll it in the sugar on the parchment paper. You may need to sprinkle the sugar directly onto the log or press some of the sugar into spots to get it to stick to the dough
• Slice the log with a sharp knife into 1/2-inch rounds and place them on a cookie sheet about 2-inches apart. Bake the cookies for about 15-17 minutes. The bottom of the cookie will be light golden brown. If the cookies are brown on top reduce the baking time by 1-2 minutes.
• Remove the cookies from the oven and let them cool on the cookie sheet for 5 minutes then use a spatula to move them to a cooling rack.
• Repeat these steps with the second log, adding more sugar to the parchment paper if required.

Storage

• Store the cookies in airtight container for up to 2 weeks. The cookies taste even better on the second day.