Roughly chop the chocolate. Heat milk and cinnamon in a pot at low heat. Add chocolate and dissolve in it while stirring. Remove the cinnamon and drain well. Put the chocolate mixture into a bowl and let it cool down for about 45 minutes.
Whip the cream until stiff, fold into the chocolate mixture in portions. Pour into a bowl, cover and leave to cool for approx. 3 hours. Finely crumble the speculoos. Sprinkle the mousse with speculoos. Serve with some caramel sauce.