Preheat oven to 180 degrees Celsius. Grease and line a 20cm/8 inch sponge cake tin with baking paper.
Whisk the eggs with a mixer until pale, fluffy and thickened. Add sugar and beat until completely mixed and dissolved. Add the cold water and fold with a metal spoon.
Place the salt, corn flour and baking powder in a metric cup, then fill to the top with plain flour. Sieve the dry mixture three times. Gently fold into the wet mixture.
Pour mixture into prepared tin. Bake for 20 minutes or until the cake springs back when lightly touched in the centre. Cool in tin for 5 minutes, then turn onto a wire rack. Remove to cool completely.
Slice sponge in half and spread whipped cream between halves. Combine icing sugar and pulp and whisk until well combined. Spread over top.