In a medium mixing bowl, sift together the flour, baking powder, ginger, cinnamon and nutmeg. Stir to combine and set aside.
In the bowl of a stand mixer fitted with the paddle attachment (or using a hand mixer), beat the dairy free butter, dark brown sugar and golden syrup together until smooth and creamy.
Slowly add the dry ingredients to the butter mixture, mixing on low speed until a soft, crumbly dough begins to form.
Lightly dust a sheet of baking paper with flour and turn the dough out onto it. With floured hands, press it together into a ball, then flatten into a round disc.
Roll the dough out to about 5mm thick, flouring the rolling pin if it sticks. Place another piece of baking paper on top, then transfer the dough to the fridge to chill for 30 minutes to 1 hour. (Chilling helps the cookies hold their shape.)
Preheat the oven to 180°C (350°F) and line a large baking tray with baking paper.
Remove the dough from the fridge and use your favourite cookie cutters to cut out shapes. Place the shapes onto the prepared tray, leaving a little space between each. Gather up any leftover dough, roll it out again, and continue cutting until all dough is used (you may need to do this in batches).
Bake for 8-11 minutes, or until the edges are just starting to turn golden. The centres should still look soft.
Let the cookies cool on the tray for 5-10 minutes before transferring to a wire rack to cool completely.
Make the easy icing. In a small bowl, combine the icing sugar and vanilla. Add water a few drops at a time until you have a thick, pipeable consistency. It should be firm enough to hold its shape when piped.
Decorate the cookies. Spoon the icing into a piping bag fitted with a small round tip and pipe your designs onto the cooled cookies. Leave the icing to set at room temperature overnight to harden completely before stacking or storing.