Pre heat oven 190 C or 170 C fan forced. Line 2 6cm x 20cm round cake tins with baking paper.
Separate egg yolks and whites. Beat egg whites until peaks form.Slowly add caster sugar. Continue to beat until mix is stiff and sugar is dissolved.
Add the egg yolks. Beat until well blended.
Sift together corn flour, plain flour and baking powder. Fold dry ingredients into the eggs with a metal spoon, gently up and down and over movement. DON,T STIR. Tap the raw mixture on the bench to get rid of air bubbles before putting in the oven.
Sponge is cooked when it springs back when it is touched lightly in the middle. Allow to cool in the tin for 5 minutes. Loosen the sides and turn onto a cake rack. Remove lining paper and turn right side up.
Serve Plain with just a sprinkle of icing sugar, or whipped cream and fresh fruit as an alternative.