Melt chocolate and coconut oil (if using) in microwave in 30 sec increments, mixing each time until just melted.
Put all ingredients together and blitz with stick blender until completely smooth.
Put in container of choice and refrigerate for softer mousse, or freezer for a bit firmer. Just let it soften a bit before serving from freezer. You can also use icey pole molds (add a little more milk for this option so it’s pourable).