In a 9 x 13 inch pan (or a pan large enough to fit in your freezer shelf) freeze the mixture. When almost frozen, scrape with a fork to break up the ice. Re-freeze for another 1 1/2 to 2 hours, scrape again with a fork and return to freezer. When frozen, serve or transfer to a plastic container for later. If using later, allow to melt slightly then scrape again with fork and serve.