Step 1

Preheat oven to 180°C. Grease two 20cm round cake pans.

Step 2

Sift the plain flour, cornflour, cream of tartar and bicarbonate of soda into a large bowl. Sift twice more, then set aside.

Step 3

In a clean, dry bowl, whisk the eggwhites with electric beaters until soft peaks form. Gradually add the caster sugar, whisking constantly, until you have stiff peaks. Add the yolks, one at a time, and whisk until thick and pale.

Step 4

Using a large metal spoon, fold in the vanilla seeds. In 3 batches, gently fold in the dry ingredients until just combined.

Step 5

Divide the mixture between the cake pans, then bake for 20-25 minutes or until the top springs back when lightly touched. Remove from the oven and cool in the pan for 5 minutes, then turn out onto a wire rack to cool completely.

Step 6

Once cool, thickly spread the jam on top of one of the cakes, then top with whipped cream. Sandwich with the remaining cake, then dust with icing sugar and serve.