Combine the flour, ginger, pumpkin pie spice, cinnamon, baking powder, coriander, and salt together in a bowl and whisk them together to aerate them. Set the bowl aside. Set up a stand mixer with the paddle attachment and combine the butter and brown sugar in its bowl. Beat them together thoroughly, then add in the eggs one at a time. Turn the speed to low and slowly add in the dry ingredients until a soft dough forms. Wrap the dough in plastic and chill it for three hours in the refrigerator.

Take the dough out after the three hours is up and let it become a little pliable for a couple of minutes. Pre-heat the oven to 350 and line two sheet trays with silicone mats. Cut the dough in half and put half back in the refrigerator to stay cold. Turn the other half out onto a well floured surface and use a floured rolling pin to roll it out to be 1/8-1/4 inch thick. Use a fairy shaped cookie cutter to cut as many cookies out as possible. Dip the cutter in flour if needed to keep the edges clean. Roll the scraps out and cut out even more. Transfer the cookies to the sheet trays, with about 8-10 per sheet.

Brush each cookie lightly with the milk and sprinkle them all very generously with the green sugar. Bake them for 10-12 minutes, until the edges start to brown and the cookies are slightly crisp. Let them cool for a couple of minutes before transferring them to racks to finish cooling. Repeat the whole process with the other half of dough. Seal the cookies in tins and leave them for Santa to enjoy!