Step 1

Preheat oven to 200°C. Grease two deep 20cm round cake pans. Dust pans with the extra cornflour; turn pans to coat evenly. Shake out excess flour.

Step 2

Beat eggs and caster sugar with an electric mixer for 7 minutes or until thick and creamy. To test when the mixture is thick and creamy, turn off the mixer then lift the beaters; the mixture should form thick ribbons. (if you are using hand-held electric beaters, use a small bowl for beating the eggs and sugar, then transfer to a large bowl to stir in the dry ingredients).

Step 3

Sift cornflour, custard powder, cream of tartar and bicarb twice onto a piece of baking paper. Sift flour mixture a third time evenly over egg mixture. Using a balloon whisk or large metal spoon, quickly and lightly fold flour mixture through egg mixture until combined. Pour mixture evenly between pans; tilt pans to spread mixture to the edge.

Step 4

Bake sponge cakes for 20 minutes or until they spring back when pressed lightly in the centre. Turn immediately onto wire racks covered with baking paper. Cool.

Step 5

Beat cream and icing sugar with electric mixer to soft peaks.

Step 6

To assemble, place one cake on a serving plate; spread with 2 tbsp jam top with sliced strawberries then one-third of the whipped-cream. Spread second cake with 2 tbsp jam then place, jam-side down, onto filling.

Step 7

Cover top and side of sponge cake with remaining whipped cream. Dot with remaining jam (you may need to warm and cool it first); using a palette knife, smooth the surface, blending jam and cream. Decorate with extra halved strawberries.