Preheat oven to moderately hot (200°C/180°C fan-forced). Grease two deep 22cm round cake pans; lightly flour the pans with a little plain flour and shake out excess flour. Beat eggs and sugar in a small bowl with an electric mixer until thick and creamy, about 7 minutes. It is important to use a small bowl for the initial beating to achieve the maximum volume.
To test if the mixture is ready, turn off the mixer, lift the beaters and the mixture should form thick ribbons. Transfer mixture to a large bowl.
Sift dry ingredients together twice onto paper. Sift flour mixture a third time evenly over the surface of the egg mixture. Using a balloon whisk or large metal spoon, quickly and lightly fold flour mixture through egg mixture until incorporated.
Pour mixture evenly into the prepared pans, tilt the pans to spread mixture to the edge. Bake sponges in a moderately hot oven for about 20 minutes or until the sponges spring back when touched lightly in the centre. Turn immediately onto wire racks, cool right way up.
Beat cream and essence in a small bowl with an electric mixture until firm peaks form. Place one un-iced sponge on serving plate, spread with jam and whipped cream; top with sliced strawberries.
ICING: Sift icing sugar into a medium heatproof bowl; stir in butter and passionfruit to form a firm paste. Add milk gradually; a small amount can alter the consistency. Stir over simmering water until icing is a pouring consistency.
Quickly spread warm Icing over the remaining sponge; place on top of the strawberries. Stand for about 15 minutes or until set.
Unfilled sponge suitable to freeze. Icing suitable to microwave.