Prepare the syrup. Combine the ingredients, stirring, over medium heat, until the sugar melts. When it comes to the boil reduce the heat to very low and after 2 minutes remove from the heat and cool.
To prepare the dough, put the water, butter and salt in a heavy pan. Bring to the boil, add both flours, the semolina and arrowroot, stir once, then remove from the heat and stir thoroughly