Place the butter, syrup and sugar in the small saucepan and heat until the butter has melted and the sugar has dissolved. Whisk together until fully incorporated.
Set aside to cool slightly.
Sift the flour, bicarbonate of soda, ginger and cinnamon into the large mixing bowl.
Pour in the buttery syrup mixture and stir to combine, then use your hands to bring together to form a dough. Add up to 1 tbsp of milk if needed. The dough will be soft at this point, but it’ll firm up in the fridge.
Place the dough on a sheet of baking paper, shape into a rectangle, and lay another sheet of paper on top of it.
Roll the dough out to a thickness of 5mm.
Transfer to a baking sheet to keep it flat, leaving the baking paper in place, then chill in the fridge for 1 hr.
Heat the oven to 190C/375F/gas 5 and grease the baking sheets with butter.
Remove the dough from the fridge and carefully peel off the top layer of baking paper.
Cut out shapes using a cookie cutter.
Place the shapes, spread apart, on the baking sheet. If you want to use the gingerbread shapes to decorate your Christmas tree, use a skewer to make a hole about 1cm from the edge, spreading the hole out a bit so it will take the ribbon or cord you want to use to hang them up.
Bake for 10-12 mins. (Depending on the size of the cutters you use, they might need a few minutes more or less cooking in the oven).
Remove from the oven and leave to cool completely on the baking sheets.
Meanwhile, mix the icing sugar with a few tablespoons of water – you want to create a consistency that’s thick but pipeable.
Spoon the icing into the piping back and decorate the gingerbread as you wish.