Very Raspberry Granita

1 1/2 cups water
1/2 cup sugar
3/4 pound fresh or frozen raspberries, (about 2 generous cups)
1/2 cup raspberry preserves, (optional)
2 1/2 T. fresh lemon juice

Bring water and sugar to a boil in a pan. Reduce heat to a simmer and when
the sugar has dissolved, stir the raspberries into the syrup and allow to cool. Place the preserves, if using in a food processor along with the raspberry syrup and puree. Press the mixture through a fine sieve, discarding the seeds. Stir in the lemon juice. Pour the granita in a wide shallow metal pan. Cover with lid, foil or plastic and allow to freeze for one or two hours, until it has frozen around the edges. Take container out of freezer and scrap the ice with a fork, mixing it from the edge to the center. Repeat this scraping and mixing process every 1/2 hour or so, at least 3 times until the entire mixture has turned into small sequined ice flakes. Serve at once. Quick Method: Pour the granita mixture into ice trays and cover with plastic wrap. Allow to freeze solid. Process the cubes in a food processor when ready to serve. The raspberry preserves give this granita a luxurious richness. If you like, drizzle a little creme de Cassis over the granita and serve it with tuiles and a dollop of creme fraiche.