Combine milk and double cream in medium-sized saucepan. Add cinnamon stick, maple syrup and vanilla extract. Slowly bring to boil over low heat to infuse for 5mins, then remove cinnamon stick.
Put chopped chocolate in jug; pour hot milk mixture over and whisk until smooth. Return to pan and gently reheat over low flame, whisking constantly, until just below boiling point. Serve immediately.