Whisk the eggs, yolks, sugar, salt and vanilla together by hand in the bowl of your electric mixer, then place the bowl over a saucepan of simmering water, stirring constantly until the mixture reaches 120 degrees. Do not overheat this mixture or the eggs will not whip properly!
Place the bowl back onto your mixer and using the whip attachment whip the eggs at high speed until they are light in color and increased in volume. You should be able to make a line in the eggs and have it remain briefly.
While you are whipping your eggs measure out your flour and cornstarch, use a strainer with an open mesh to sift the mixture together.
Remove the bowl from the mixer and sift ⅓ of the mixture into the eggs, and fold it into the eggs using a rubber spatula. Make sure you go to the bottom of the bowl frequently, the flour will settle to the bottom.
Repeat this procedure with flour, ⅓ at a time until it is all folded in.
Divide the mixture into two prepared baking pans, tilt the pans in a circular motion and bring the batter close to the top as it goes around, this will help prevent the cake from crowning.
Bake for approx. 30 minutes until the cake is well risen and firm to the touch. A knife inserted in the center should come out clean.
Allow the cakes to cool, then run a sharp knife around the edges to help it release from the pan, and place on a plate to finish cooling.
Split the layers in half with a serrated knife and set aside until needed.