Preheat the oven to 180oC/160oC fan/350oF. Line a couple of baking sheets with baking paper or non-stick liners.
Cream the butter and sugar in a bowl until smooth. Add the egg and preferred syrup then beat again to combine fully. Stir in the flour, cocoa, cinnamon, baking soda and salt so you get a soft dough. Roughly chop the chocolate into chunks then fold into the dough.
Pour about 50g (1/4 cup) of extra granulated sugar into a wide, shallow bowl. Scoop heaped tablespoons of dough, roll into balls and roll in the extra granulated sugar to coat. Place on a baking sheet spaced about 5cm (2 inches) apart.
Bake for 10-12 minutes until the cookies have spread well and are slightly crinkled. Let cool on the baking sheet for a few minutes so they can set before transferring to a wire rack to cool completely. Repeat the rolling and baking to use all the dough.
Store cookies in an airtight container for up to 5 days.