Heat the oven to 180°C. Grease and base line a 20cm round cake tin.
Put the eggs and sugar in a mixing bowl and beat well. Add the egg yolks and whisk until pale and thick.
Stir in the flour, potato starch and cocoa. Mix well. Pour into the prepared cake tin.
Bake for 45 minutes until set. Cool and place on a wire rack. Cover with the frosting desired.