Small saucepan: mix cocoa, sugar and coffee. Add water, whisk while bringing
to a boil. Turn down, simmer for 5 minutes or so until the mix thickens,
whisking continuously, otherwise it will boil over.
Off the heat: add the evaporated milk, alcohol and vanilla. Stir. Let cool
completely, then put in freezer till chilled and quite firm, about 3-4 hours.
If you have a hand crank ice cream maker, use it. Crank for about 20 minutes or
until thick, and then place in freezer overnight. By then, it will have an
edible consistency.
If you don't have a hand crank, then place in a glass dish. Put in freezer,
stirring every hour or so till the texture is as soft ice cream. Let freeze
overnight. This will be icier - like granita.