A light-as-air sponge glued together with thick cream and drizzled with chocolate icing. Heavenly. INGREDIENTS5 extra-large eggs200g (1 cup) caster sugarGrated zest and juice of 1 lemon100g ( cup) cake flour50g cornflourpinch of saltFilling250ml (1 cup) cream80ml caster sugarTopping40g cocoa powder100g ( cup) icing sugarBoiling waterMETHODPreheat oven to 180°C.Spray a 23cm cake pan with cooking spray.Separate yolks from egg whites and beat the whites until stiff but not dry. Gradually beat in half the caster sugar.In a separate bowl beat egg yolks, lemon zest and juice until fluffy and light, then gradually beat in remaining sugar. Continue beating until mixture is thick and creamy.Fold the egg white mixture into the yolk mixture.Sift the flour, cornflour and salt together twice, fold into the egg mixture, then pour into the prepared tin.Bake for 40-60 minutes.Remove from the oven and leave in tin for5-10 minutes, then turn out onto a rack and cool completely.To make the filling, beat cream and caster sugar together until thick.Slice cake in half horizontally and sandwich cake halves together with the cream.To make the topping, sift together cocoa powder and icing sugar. Mix with a little boiling water a teaspoonful at a time to get a fairly runny glaze.Stand to thicken slightly then pour over the cake, allowing the icing to drip down the sides...