Cook sugar and water together in a small saucepan until a drop of syrup forms a soft ball in cold water.
Beat egg yolks until thick, then add hot syrup very gradually, continuing to beat until mixture has cooled.
Add salt and vanilla.
Chill until thickened, then fold in the stiffly beaten cream.
Pour into a flat pan or freezer tray and freeze until firm.
To serve, alternate layers of frozen-cream mixture and any suitable sauce in tall parfait glasses; garnish top.