Sift flour, salt, bicarbonate of soda and spices together in a large bowl.

Put the butter, sugar and golden syrup in a large bowl and mix with a sturdy wooden spoon until pale and creamy.  Alternatively, mix in a large stand mixer. 

Add the egg and egg yolks in a slow stream and mix until well combined. 

Add the dry ingredients, in three batches, until thoroughly mixed.  Divide the dough into four portions and flatten each piece into a rough disk. 

Cover in plastic wrap and refrigerate until firm or for up to three days.

Preheat oven to 170°C. Line several large trays with baking paper, set aside.

Remove dough from the refrigerator and allow to soften slightly.  Roll out each disc between two sheets of baking paper until about 3mm thick. 

Cut into desired shapes using biscuit cutters or a knife. Continue to re-roll to make use of all the dough.

Place the shapes on a baking tray lined with baking paper and bake, in batches for 15-20 minutes or until golden.  Allow to cool on trays.