Finely grind the desiccated coconut with the icing sugar in a coffee grinder or food processor. Mix together the flour and matcha powder, then add to the coconut mixture. Add the remaining ingredients and a pinch of salt, and quickly knead everything to a smooth dough. Wrap and leave in the fridge for at least 30 mins.
Heat the oven to 160C/140C fan/ gas 3. Roll out the dough on a floured work surface to a thickness of about 5mm and, using the tree-shaped cutter, press out the trees. Put them on baking sheets lined with baking parchment and bake for about 10-15 mins. To make sure they stay nice and green, the trees should hardly be browned. Remove from the oven and leave to cool.
For the icing, tip the icing sugar into a small bowl and gradually add the milk, stirring until smooth. Add a few dops of food colouring, if you like. Decorate the biscuits with it, then sprinkle with desiccated coconut. Set aside until completely dry. Will keep in an airtight container for up to three days.Recipe adapted from Let it Snow by Agnes Prus (£7.99, Hardie Grant). Photographs © Frauke Antholz.