The time it takes to freeze the granita will vary depending on the temperature of your freezer. If there is enough space in the freezer to do so, dividing the mixture between two pans will speed up the process.
Note: These recipes have been adapted from 'Granita Magic: 55 Ices For Every Reason and Every Season Always the Perfect Thing To Serve' by Nadia Roden. Copyright 2003 by Nadia Roden. Watercolors copyright 2003 by Nadia Roden. Photographs copyright 2003 by D. James Dee. Reprinted by permission of Artisan.