Cook syrup over medium heat, stirring constantly, until syrup reaches thread stage (230°). Remove from heat.
Beat egg whites (at room temperature) until stiff peaks form. Pour syrup over beaten egg whites, and continue beating until mixture is cool. Chill.
Beat whipping cream in a large bowl until soft peaks form. Fold chilled syrup mixture into whipped cream. Spoon mixture into an 8 - inch square pan; freeze overnight. Scoop into individual bowls, and top with toasted pecans, if desired.