Whisk the eggs and sugar with a ballon whisk in a bowl over a pan of hot water.

Continue until the mixture is light creamy and double in.

Remove from the heat and whisky until cold and thick.

Fold in the flour very gently.

Grease a swiss roll tin and line with greasedproof or silicon paper.

Turn out on to a sheet of paper sprinkled with additional caster sugar.

Remove the paper from the swiss roll with warm jam

Immediately roll up as tight as possible and leave to cool completely.