In a mixing bowl, add flour, cocoa powder, espresso powder, salt and baking soda. Sift all these ingredients and keep aside. In another mixing bowl, add butter, brown sugar, granulated sugar, egg white and vanilla extract. Mix everything until you have a rough and chunky mixture. Add the sifted flour mixture into the wet ingredients. Mix everything until you have a crumbly mixture. At this point, stop the mixer and knead the mixture with your hands into a ball of dough. If the dough is still a little dry and crumbly, add some milk or water (1 teaspoon at a time) to the dough and knead again. Take little portions of the dough and make little balls. Roll them in a plate full of granulated sugar. Place the cookie balls on a lined with parchment paper and bake at 350 degrees F for about 8-10 minutes or until the sides are slightly crispy. Let these cookies cool down on a cookie tray. Then, store them in an airtight plastic container at room temperature for up to 3 days. And you are done!