Photograph: Karen Thomas
Place the double cream and crushed chillies in a pan and bring to just below boiling point. Cover the pan and leave to infuse for 30 minutes.
Break up the chocolate into small pieces. Tip into a mixing bowl and add the butter, stem ginger, ginger syrup and a pinch of salt. Reheat the infused cream gently until almost boiling, then strain through a sieve on to the bowl of chocolate.
Leave to stand for a minute or so to allow the chocolate and butter to melt, then stir until glossy and well combined. Cover and chill until set – around 3 hours.
Sift the cocoa into a shallow bowl or dish. Use a teaspoon to scoop out a few truffles at a time, then roll into a ball with your hands and drop into the bowl of cocoa. Roll in the cocoa until coated, then place on a tray lined with baking paper. Chill in the fridge until ready to serve, or freeze.
Get ahead: the truffles can be made up to a month ahead and stored in an airtight container in the freezer. Remove from the freezer an hour before serving.
Kitchen secret: adjust the amount of chilli to suit your tastes; ¼ tsp provides a pleasant heat without overwhelming the ginger flavour – increase to ½ tsp if you want more of a kick. Make sure that you use chocolate with a high cocoa-solid content, both for flavour and a good consistency.