Line a 20 x 30cm tin with baking parchment. Mix the biscuits with most of the ginger, then set aside. Melt the chocolate, butter and golden syrup in a bowl set over a pan of simmering water, stirring occasionally, until smooth and glossy. Pour this over the biscuit and ginger mixture and mix together well.
Tip the mixture into the prepared tin and sprinkle over the reserved ginger, then flatten the top lightly – it doesn’t need to be completely smooth. Chill for at least 2 hrs, or overnight, before cutting into small squares.
These squares will last in the fridge in an airtight container for a week, or freeze for up to a month. Keep them chilled until you pack them up to give away, so that they don’t melt while you’re transporting them.