In a mixer fitted with a paddle attachment cream the butter and brown sugar until light and fluffy.
Reduce the speed and mix in the ginger, mixed spice, salt and golden syrup before adding the egg. Mix well.
Combine the flour, baking soda and baking powder in a sifter and sift into the mixture and mix until just combined.
Remove the mixture from the bowl and wrap in glad wrap and put in the fridge for at least 1 hour.
Preheat the oven to 180 degrees celsius and roll out the gingerbread dough onto a floured work surface.
Use your favourite cookie cutters and cut the dough into shape and place onto a baking tray lined with baking paper and bake for 12 minutes before transferring to a wire rack to cool.
Make the Royal Icing
In a mixer fitted with a paddle attachment beat the eggs until stiff.
Add the icing sugar and lemon juice and beat for 1 minute.
Decorating the Gingerbread Christmas Tree Cookies
Add green food colouring to the royal icing until you reach your desired colour.
Using a spatula ice the cookies in batches (approximately 6 at a time) and sprinkle with the sanding sugar.