Cream together the butter, sugar and golden syrup in a large bowl until smooth. Beat in the egg. Add the salt, ginger, cinnamon and cardamom to the bowl and mix in well. Add the flour, bicarbonate of soda and baking powder and mix together until a soft dough forms.
Chill the dough for at least 2 hours until firm.
10 minutes before removing the dough from the fridge, preheat the oven to 180oC (350oF)
Divide the chilled dough in half. Roll out one half on a large piece of baking paper, sprinkling with flour underneath and on top as needed, using a lightly floured rolling pin. Roll until the dough is about 4mm (1/8 inch) thick. Stamp out shapes using cookie cutters - mine were 5cm (2 inches) diameter - dipping them into flour if needed to prevent them sticking.
Transfer the cut shapes to a baking tray lined with baking paper. Bake for 8 minutes (for 5cm/2" diameter cookies). Once baked transfer to a wire rack to cool.
Repeat the rolling and cutting with the rest of the dough, re-rolling scraps as needed.
Place the icing sugar into a medium bowl. Add lemon juice 1 tsp at a time until you get a thin glaze. Dip the top of each baked cookie into the glaze and place glazed side-up onto a wire rack so the excess can drip off. Leave for at least 1 hour so the glaze can set. Once set, store in an airtight container for up to 5 days.