This is the mousse recipe my grandmother (Mutti) would make. It's excellent as a mousse or even as a pie filler. Just pour it into a pre-cooked pie crust for an amazing chocolate pie.
The original recipe calls for rum, but I prefer to use 1-2 tablespoons of vanilla extract instead.
Better chocolate yields better results, so buy your favorite or chop up a quality bar of chocolate rather than using the cheap stuff (unless the cheap stuff IS the good stuff!). Also, you can mix dark and semi-sweet for a richer, darker mousse.
After making this recipe many times I find that it pays to have everything ready to go rather than strictly moving from step to step. If you can manage without burning the milk, whip the cream while waiting for milk to boil (and for the ice to melt in the blender if you need more time). If you don't do it all serially, this takes very little time and effort to make for how well received it always is!