Ingredients
- 50g butter, softened, plus extra for greasing
- 200g caster sugar
- zest 2 lemons or 2 limes or 1 grapefruit
- 100ml lemon, lime or grapefruit juice, or a mixture
- 3 large eggs, separated
- 50g plain flour
- 250ml milk
- icing sugar, for dusting (optional)