Coarsely chop the chocolate.
Melt the chocolate, whipping cream and sugar in a double boiler.
Place the chocolate, whipping cream and sugar in a metal bowl over the saucepan, making sure the bottom of the bowl doesn't touch the simmering water.
Turn the heat down to low and melt the chocolate, stirring constantly and making sure the chocolate doesn't burn.
Pour the mixture into a fondue pot and stir in the cinnamon, chilli powder, and rum.
Keep the fondue warm on low heat.
Swirl in the sour cream just before serving.
Get a flirt fix with a dessert made for romance: rich, dark chocolate fondue with fruit dippers.