In a large mixing bowl use a whisk to combine the flour, spices, baking soda and salt. 
In another mixing bowl add the sugar, butter, sweet potato puree and syrup and beat on a medium to high electric beater setting until well combined (around 2 minutes). 
Add the egg and vanilla extract and beat on a low to medium setting until combined. 
Add the dry mix to the wet and use a spatula to fold through to combine into a dough. 
Turn the dough out onto a lightly floured surface and shape into a ball. Cover with cling wrap and place into the fridge for 1 hour or until firm. 
Preheat an oven to 180 degrees and line a baking tray with parchment paper. 
Turn the dough out onto a lightly floured surface and knead a few times in the flour until it is not sticky. 
Roll the dough out into a rectangle which is even, smooth and only around ½ an inch thick. 
Use cookie cutters to cut out cookie shapes and carefully transfer them to the baking tray. 
Repeat this process until all of the dough is used and the tray is full. Roll the leftover dough into a ball and roll out again to keep reusing the same piece of dough until all is cut out into cookie shapes. 
Place the cookies in the oven to bake for 15 minutes or until they are fragrant in smell and golden to look at. Remove from the oven and allow them to cool for 15 minutes on the tray until transferring to a wire rack to cool completely. 
When the cookies have cooled completely, dust them with icing sugar and store in a dry place in a plastic container with a lid for up to 1 week.