Heat the oven to 180C / 400F and line your baking sheets with some baking parchment.
Melt the butter, sugar, golden syrup and treacle in a saucepan, over a medium heat. Stir from time to time until everything has melted and stirred well to combine.
In a small bowl, dissolve the bicarbonate of soda in the just boiled water.
In a large bowl, mix all the dry ingredients together. Pour over the butter, sugar mixture and the bicarbonate of soda. With a wooden spoon, mix everything together until you have a dough.
Divide the dough to make it easier to work with. Roll out each part to about 3mm thick. Try doing this without flour to avoid making the dough dry. Cut out with your Christmassy cutters and place on the lined baking tray.
Bake for about 8 minutes until just starting to colour. Remove from the oven and make a hole in the top with a wooden skewer. Leave to cool before decorating.
Make the icing by beating the egg whites and icing sugar together until glossy and smooth, add the squeeze of lemon and mix it in.
Decorate the biscuits and if you’re hanging them on the tree, thread with some ribbon or string.
Please note this dough is easier to handle when freshly made. It is slightly trickier to work with when cold, but still makes delicious biscuits!