Preheat the oven to 180ºC / fan oven 160ºC / gas mark 4. Grease a 1.4 litre / 2 1/2 pint deep
oven proof dish. Cream together the butter and sugar until light and fluffy. Stir in the lemon and
lime zest and juice and the egg yolks (the mixture will curdle at this stage, but don't worry),
then beat in the flour and milk.
In a separate bowl, whisk the egg whites until standing in soft peaks. Stir a quarter of the egg
whites into the mixture to lighten it, then gently fold in the remainder.
Turn into the prepared dish. Stand the dish in a roasting pan with enough water to come 2.5cm /
1 in up the sides of the dish. Bake for 30-35 minutes, until risen with a pale golden crust.
Dust with icing sugar and serve warm with pouring cream.