1. Preheat oven to 160°C. Line 2 baking trays with nonstick baking paper.
2. Place golden syrup, sugar and butter in a medium saucepan over low heat and stir until butter melts. Remove from heat. Set aside until cooled.
3. Sift the flours, bicarbonate soda, ginger and mixed spice into a bowl.
4. Add egg yolk to golden syrup mixture and stir until combined. Add sifted flour mixture in 2 batches, stirring after each addition until just combined. Use your hands to bring the dough together.
5. Roll level tablespoons of dough into balls. Place on lined trays, 3cm apart, then into the oven to bake. If necessary, swap the trays halfway through cooking to ensure an even colour. Bake for 12-15 minutes or until golden. Set aside on trays for around 30 minutes to cool.
6. In a heatproof bowl, combine the icing sugar, cocoa powder (if using), vanilla essence, extra butter and enough milk to form a paste. Place the bowl over a saucepan of simmering water (bowl should not touch water). Stir with a metal spoon for 3-5 minutes or until smooth. Remove pan from the heat, leave bowl in place to keep icing runny. Dip top of each biscuit in icing, then sprinkle with hundreds and thousands, place on a baking tray lined with non-stick baking paper. Place aside for 15 minutes to set.
Tip:
For chocolate icing, add 2 tsp cocoa powder to the mixture. We made half with white icing then added 1tsp cocoa powder to make the remaining icing chocolate.