In a chilled large mixing bowl combine whipping cream, sugar, and vanilla. Beat with an electric mixer on medium speed until soft peaks form; set aside.
Divide half of the crumbled brownies between 4 large parfait glasses or water goblets. Divide half of the raspberries, ice cream topping, and whipped cream between the glasses, creating layers. Repeat layers with remaining brownies, raspberries, ice cream topping, and whipped cream. If desired, sprinkle with cocoa powder. Serve immediately or cover and chill up to 4 hours.