In a stand mixer, beat the eggs and sugar on high speed for about 25 minutes until thick, pale, and tripled in volume. Sift the flour and cornstarch together.
Gently fold the dry ingredients into the egg mixture using a rubber spatula, being careful not to deflate the batter. Add vanilla extract and mix gently.
Pour the batter into a buttered and floured baking pan. Bake in a preheated oven at 325°F (160°C) for 45–55 minutes until golden and a toothpick inserted comes out clean.
Remove from oven, cool slightly, then invert onto parchment-lined tray. Cool to room temperature. Ready for slicing or layering.