For marshmallows, place gelatine in the bowl of an electric mixer fitted with a whisk attachment, add 1/3 cup cold water and stand for 10 minutes. Combine sugar, corn syrup and 1/3 cup water in a saucepan and stir over medium-high heat until sugar dissolves, bring to the boil and cook without stirring until mixture reaches 121C on a sugar thermometer. With the mixer on low speed, add syrup in a thin steady stream and whisk until combined. Scrape down sides of bowl, add vanilla, increase speed to high and whisk for 8-10 minutes or until thick, white and fluffy. Sieve over 20gm cocoa, whisk and transfer mixture to a baking paper-lined, lightly oiled 17cm-square cake pan, smoothing top and stand overnight. Turn onto a lightly oiled cutting board and cut into squares. Sieve together icing sugar, cornflour and remaining cocoa, then roll marshmallows in cocoa mixture to coat. Marshmallows will keep for up to a week in an airtight container.
Combine milk and cream in a heavy-based saucepan and bring to a simmer over low heat. Add chocolate and stir continuously until melted and smooth. Divide among heatproof cups, add liqueur to taste, scatter with cocoa and serve with marshmallows.
Note Corn syrup is available from health food stores and