1.Preheat oven to 180°C/160°C fan forced. Grease a 1.5-litre (6-cup) ovenproof dish.
2.Whisk butter, zest, juice, milk, flour, caster sugar and egg yolks in a bowl until combined.
3.Using an electric mixer, beat egg whites in a clean, dry bowl until soft peaks form. Fold half the egg white mixture into lemon mixture. Fold in remaining egg white until just combined. Spoon into prepared dish.
4.Sprinkle berries over top of pudding Place dish in a large roasting pan. Pour enough boiling water into pan to reach halfway up side of dish. Bake for 35-40 minutes or until just set at centre. Remove from oven. Remove dish from pan.
5.Serve pudding dusted with icing sugar.