Cream the butter and soft light brown sugar in a mixer.
Add the cinnamon and ginger, finely grated orange zest, black treacle and beat again, then add the milk.
With the beater on a low speed add the plain flour and the bicarbonate of soda.
Scrape the dough off the beaters and, using your hands, bring the dough together into a ball, adding more milk if you need.
Wrap in clingfilm and chill for an hour.
Roll the dough out 3mm (⅛in) thick.
Stamp out your shapes and put them onto two lightly buttered baking sheets. Gather the remaining dough, roll out again and keep cutting until all of it has been used.
Chill for 45 minutes.
Cook the biscuits for 12 minutes in an oven preheated to 180C (350F, gas mark 4). They should start to feel hard round the edges as they cool and eventually become hard – they need to have a nice 'snap'.
Gently beat 1 egg white then add as much icing sugar as needed (about 350g/12oz) to give you a mixture thick enough to pipe (thinner if you are just going to drizzle it onto the biscuits).
Decorate the biscuits and leave to set.
If gifting, wrap in cellophane and tie with ribbon. Makes 24.
TIP: practice your piping beforehand, if you are not used to it. For an easier topping drizzle the icing using the tines of a fork.
For more great festive recipes, see our Christmas baking ideas.