I have found recipes by Alice Medrich (in Pure Dessert) and Mark Bittman (How to Cook Everything) that look very similar: both use cocoa only, with water and sugar and vanilla extract, plus optional other flavorings (rum/vodka). Then there is a recipe credited to Claudia Fleming on the Scharffen Berger website, that uses cocoa and a hefty amount of bittersweet chocolate, along with sugar and water. Has anyone tried these? Comments on the best one? How long does it hold in the freezer?