1. Simmer 3/4 cup water and 3/4 cup of the sugar in a saucepan for 10 minutes. Mix the coffee with a little water to form a paste, stir in and allow to cool.

2. Add 2 cups water and the liqueur. Pour the granita into a shallow plastic or metal container and allow to freeze overnight.

3. Dissolve the gelatin powder in 2 tablespoons cold water. Scrape the vanilla seeds into a saucepan and add the beans, milk, cream and remaining sugar. Bring to a boil, strain into a bowl and discard the beans.

4. Add the gelatin to the hot milk mixture, then stir to melt. Place the bowl inside a bowl of ice water and stir until the gelatin begins to set (as the spoon is drawn through it, you will see a line across the base of the bowl). Pour into four small (2/3-cup) gelatin molds or ramekims Chill overnight.

5. Half an hour before serving, refrigerate four plates. Release the panna cotta. from the molds by wrapping in a hot cloth and turning over. Scoop out the granita in flakes by drawing the side of a metal spoon across its surface. Serve on the chilled plates with the panna cotta.