Bring all ingredients to the boil.
Mix these ingredients together. Boiled ingredients on top of the second mixture and let thicken for 1 minute (English style).
Add the hot mixture (Mixtures 1 and 2) to the cream cheese and lemon and mix well.
Whip the egg whites and caster sugar until fluffy. Fold into the cream cheese mixture. Pour into a greased mould and place a thin layer of sponge cake at the bottom. Bake in a bain marie for 30 minutes at 160°C (320 °F) at the bottom and 200°C (392 °F)at the with the steam exhaust valve open. Leave to set in the fridge overnight.