This is very good. It's rich, so you might want to add additional boiling water.
2 (1-oz) squares unsweetened chocolate
1 (14-oz) can sweetened condensed milk
4 cups boiling water
1 tsp vanilla
speck of salt
Garnish of whipped cream and cinnamon or nutmeg
Over very low heat, melt the chocolate. Whisk in the sweetened condensed milk. Gradually add the boiling water, stirring until well blended. Remove from heat and stir in the vanilla and salt. Garnish with whipped cream and cinnamon or nutmeg. Serve immediately.