Put the cocoa, sugar, salt and water in a large saucepan. Use.a whisk to blend well, then put on a medium-high heat and bring to a boil, whisking, until smooth. Boil for 15 minutes, whisking consistently to prevent scorching and boil-over.

Stir in the brandy, then remove the pan from the stove and stir in the finely chopped chocolate and the vanilla extract. Pour through a fine sieve, let cool, then chill for at least five hours.

After it's chilled, whisk to blend, then freeze in your ice cream maker. It may need to finish hardening up in your freezer. Serve at once or store in sealed container, removing from freeze about 20 minutes ahead of serving to soften.