100 ml double cream
300 ml single cream
125 g sugar (½ cup)
150 g lindt 85% dark chocolate (or similar high quality chocolate)
1 shot of dark rum. The darker the better.

Melt chocolate into about half the single cream in a double-boiler to
make a smooth mix (no lumps or bubbles, do not allow to boil). 

Remove from heat.

As it cools, mix in the remaining single cream, double cream and sugar,
producing a smooth mixture.

Add a shot of rum. Mix well.

Allow mixture to cool.

Pour into ice-cream maker, proceed as per maker's instructions.