Add the vegan butter, brown sugar, ginger, cinnamon, and nutmeg to a large mixing bowl and cream together with an electric mixer until fluffy.
Then, add the molasses, flax egg, and vanilla to the bowl and mix together.
Finally, add in the all-purpose flour and mix until a thick, yet smooth, dough forms.
Cover the bowl of dough with plastic wrap and add to the fridge to chill for 30 minutes.
Remove the dough from the fridge, preheat the oven to 350F, and line a baking sheet with parchment paper.
Next, place the cookie dough onto a sheet of parchment paper. Then, layer another sheet of parchment paper on top of the dough. Use a rolling pin to roll the cookie dough between the two sheets of parchment paper until the dough is about ½-inch thick.
Remove the top layer of parchment paper and use a cookie cutter to cut out the gingerbread cookie shapes. Take any leftover dough and continue this process of rolling out the dough and cutting out shapes until all the dough has been used.
Place the gingerbread cut out cookies onto the parchment-lined baking tray. Make sure to leave a little space between each cookie so they do not stick together. It is likely all the cookies will not fit on one baking sheet, but it is best to only cook one tray of cookies at a time for the best results.
Add the tray of cookies to the oven and bake for 8-10 minutes. For softer cookies, do not bake longer than 8 minutes.
Remove the tray from the oven and let the cookies cool on the tray for about 5 minutes. Then, transfer the cookies to a wire cooling rack to cool completely before decorating.
To make the icing mix together the powdered sugar, water, and agave until smooth. Then, add to a piping bag and decorate cooled cookies however you would like. Once the icing is on, it takes about 1-2 hours to harden completely, so make sure not to store cookies until the icing has set.
Once the cookies are decorated and the icing has set, serve and enjoy!