1.Preheat oven to moderate, 180°C (160°C fan-forced). Grease and flour a deep 23cm square cake pan.
2.Beat eggs and sugar in a small bowl with an electric mixer until thick and creamy; about 8 minutes. Transfer to a large bowl.
3.Sift cornflour, custard powder, cream of tartar and bicarbonate of soda twice onto paper, then sift over egg mixture; gently fold the ingredients together.
4.Pour mixture into prepared pan, bake, uncovered, in a moderate oven for about 25 minutes or until sponge springs back when touched lightly in the centre. Turn sponge immediately onto a wire rack lined with baking paper; turn top side up to cool.
5.Remove seeds from pomegranate. Discard flesh.
6.Best cream, icing sugar and extract in a small bowl with an electric mixer until firm peaks form. Place the sponge on a serving plate. Top the sponge with the cream mixture, raspberries and pomegranate seeds.
The sponge is best made on the day of serving.Note