Make the flax egg. In a small heat proof bowl, combine the ground flax seeds with the boiling water. Mix them together well and set aside to cool slightly. Let this rest for 5 minutes.
Sift the dry ingredients. In another bowl, sift together the flour with baking soda, salt, and all the spices. Set this aside.
Mix the wet ingredients. In a large bowl with a hand mixer, or in the stand mixer with the paddle attachment, cream the softened vegan butter until light and fluffy, about 5 minutes. Add the brown sugar, flax egg, vanilla, and molasses. Mix this well on medium speed for about a minute to really incorporate all the ingredients.
Combine ingredients. Now, add the dry ingredients to the wet. Mix on slow speed at first and then on medium until the dough comes together in the bowl.
Chill the dough. Divide the dough into two equal portions and wrap in plastic wrap. Chill the dough in the fridge for at least 30 minutes before rolling out.
Preheat the oven to 350°F/180℃. Make sure the oven rack is in the middle of the oven. Line 4 baking trays with parchment paper (number of trays will depend on size of cookies).
Roll the dough. Dust the work surface generously with extra flour. Roll the chilled gingerbread dough to about a ¼ inch thickness. Cut out cookies with your favorite cookie cutters. Use a spatula to carefully transfer them to the prepared baking trays. These cookies won’t spread that much but it’s still a good idea to leave a little room between cookies. Re-roll the dough and use until no dough remains.
Bake. Bake the gingerbread cookies for 8-11 minutes or until done. The edges will be set and a slightly darker color will be developed on the edge of the cookie. Don’t over bake these! For smaller cookies that are under 4 inches in size, I find they only take about 8 minutes. Larger cookies take upwards of 11 minutes. Remove from the oven and let cool on the hot tray for 10 minutes before transferring to a cooling rack.
Decorate. Mix together the powdered sugar and water until it is the thickness of icing that you like. Transfer to a piping bag. Decorate the cooled cookies with icing and sprinkles. Enjoy!
