2 cups whole almonds — skin on, roasted &cooled
4 cups water
5 1/2 cups sugar
3/4 cup light corn syrup
2 teaspoons lemon zest — grated
4 tablespoons almond-flavored liqueur
Pulse the almonds to a powder in a food processor. Transfer to a pot and combine with the water, sugar, corn syrup and lemon zest. Bring to a boil over medium heat, stirring occasionally. Cool completely and add the liqueur. Transfer to a 9- by 13-inch (23- by 33-cm) glass baking dish and place in the freezer. Freeze for 3 hours, stirring with a whisk every 30 minutes, until the granita has completely frozen into small granules. Serve the same day or cover and keep frozen for up to 2 days. Stir with a fork to break up the granita before serving.