In a saucepan over low heat, combine unsalted butter, golden syrup, black treacle, and light brown soft sugar. Stir until melted and dissolved.

In a large mixing bowl, whisk together bicarbonate of soda, ground ginger, ground cinnamon, mixed spice, and plain flour. Make a well in the center.

Pour the cooled butter mixture into the well and mix until a cohesive dough forms. Knead briefly.

Shape the dough into a flat disk, wrap in plastic wrap, and chill in the freezer for 15 minutes.

Preheat the oven and roll out the chilled dough to 5mm thick. Cut out shapes with cookie cutters.

Line baking trays with parchment paper and place gingerbread shapes on trays, then chill for another 10 minutes.

Bake in the preheated oven for 10-15 minutes until edges are golden. Cool on trays.

Mix icing sugar with water until thick but pipeable. Prepare for decorating.

Decorate cookies as desired, using icing to create designs and characters.