In a large bowl, whisk together the flour, salt, baking soda, cinnamon, and ground ginger. Set aside.
3 ½ cups all-purpose flour (455 grams), ½ teaspoon fine grain salt, 1 teaspoon baking soda , 1 ½ teaspoon ground cinnamon, ½ teaspoon ground ginger
In a separate large bowl, add the shaved piloncillo (or dark brown sugar), molasses, butter, egg, evaporated milk, vanilla extract. Using a spatula or your hands, mix until all ingredients are incorporated.
½ cup (98 grams) piloncillo (or dark brown sugar), ⅔ cup molasses (225 grams), 1 large egg, 3 Tablespoons evaporated milk (45 ml), 2 teaspoons vanilla extract, 2 Tablespoons unsalted butter (28 grams)
Make the dough: Gradually add the dry ingredients to the wet mixture. Mix with a spatula or your hands until a dough starts to form. If the dough is be a bit sticky—add a little extra flour (a tablespoon at a time) until it's soft but manageable.
Note: the dough will be a little sticky due to the molasses but it should not leave any residue on your hands when handling it.
Shape the dough into a flat square disk, wrap in plastic wrap, and refrigerate the dough for at least 2 hours.