Soak sago in milk for 1 hour.
Bring milk and sago to the boil and boil sago until clear.
Remove from heat and set aside.
Beat egg yolks and sugar together until light and creamy.
Add to milk mixture and mix well.
Return to low heat and stir until mixture thickens.
Set aside and allow to cool.
Beat egg whites until soft peaks form.
Fold into sago mixture using a large spoon.
Spoon into serving bowls or glasses and top with custard.