Put the butter, syrup and sugar into a saucepan and heat gently, stirring occasionally, until the butter has melted and the sugar dissolved. Take the pan off the heat and stir in the spices. Mix together the flour and bicarbonate of soda and then beat into the spicy butter mixture, adding enough milk to make a smooth dough.
Turn out the dough on to a board and leave it for 5–10 minutes until it is cool enough to handle. Knead well, then roll out on a lightly floured surface or a piece of nonstick baking paper.
Cut out Christmas shapes using star, tree, stocking, bell or any other festive cutters. Re-roll the trimmings and cut out more shapes. Transfer the shapes to lightly greased baking sheets.
Make a hole in the top of each biscuit with the end of a skewer or a teaspoon handle and bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 10–12 minutes until browned. Enlarge the hole for ribbon if needed. Allow to cool on the baking sheets.
Pipe the icing on to the biscuits, add the coloured balls, if using, and allow to harden. Thread fine ribbons through the holes on the biscuits and tie on to the Christmas tree.