In food processor, puree frozen raspberries, prunes and yogurt, scrapping down sides as needed, until smooth.
If "ice cream" is not firm, transfer to airtight container and freeze for 30 to 60 minutes or until firm. Serve in dessert glasses.
Tip: A powerful smoothie mixer makes the ice cream particularly creamy. But if you only have a hand-held mixer, throw raspberries first, then mix all ingredients together. Freeze in an ice cream maker according to manufacturer's instructions. Or, divide into 4 portions and spoon into silicone muffin moulds; freeze for 1 to 3 hours (do not let it get too hard). To serve, remove individual servings from moulds and transfer to serving dishes.