Stir together water & 1/4 cup sugar until sugar dissolves. (I added more sugar than 1/4 cup b/c raspberries are very tart when frozen).
Pulse raspberries in a food processor until coarsely chopped. With machine running, pour in sugar-water; pulse until mixture is smooth. Transfer to an airtight container, freeze until firm, about 30 minutes.
Whisk cream & remaining tablespoon sugar until soft peaks form. (This portion of the recipe did not work for me. Maybe I needed more sugar than just a tablespoon, but I ended up using cool whip).
Scoop sorbet into 4 glasses, & top with whipped cream.