Combine the slivered almonds, maple syrup, vanilla extract, almond extract and cinnamon in the bowl of a food processor or blender. Pulse until the ingredients are finely ground, about 5-7 minutes. Slowly pour the hot water through the feed tube or the lid until the mixture becomes a fine paste.

Transfer the mixture to a 9x13 glass pyrex dish. Add the cold water and stir to combine. Cover the dish tightly with plastic wrap and put in the freezer. After about a hour or so take a fork and scrape the almond ice that has started to form. Mix it as well. Cover the dish again and place back in the freezer. Remove and scrape down every hour. Once the granita is frozen solid you can scrape and place the shards in serving dishes. You can keep the granita in the the freezer in an airtight container for up to 3 days.