In a small saucepan, sprinkle gelatin over cold water; let stand for 1 minute. Bring to a boil; cook and stir until gelatin is dissolved. Remove from the heat; set aside.
In another saucepan, heat whipping cream and sugar over medium heat until sugar is dissolved and mixture is lukewarm. Remove from the heat; stir in gelatin mixture until completely dissolved. Cover and refrigerate until slightly thickened, about 30 minutes.
Stir in sour cream and vanilla. In each of four parfait glasses, place a scant 1/4 cupful of cream mixture; top each with a rounded tablespoonful of raspberries. Repeat layers. Top each with scant 1/4 cup of cream mixture.
Cover and refrigerate for 3 hours or until set. Just before serving, garnish with fresh raspberries and mint if desired.