Preheat your oven to 180°C.
In a large bowl, add the eggs, sweetener, and vanilla extract. Beat for 5 minutes, or until the mixture becomes pale yellow, thick, and fluffy.
In a separate bowl, whisk together the flour, corn starch, and baking powder.
Sift half of the flour mixture into the beaten eggs and gently fold until mostly combined. Be sure to scrape all the way to the bottom of the bowl, as flour can settle there.
Sift in the remaining flour mixture and continue folding gently until no dry streaks remain.
Pour the batter into a non-stick cake tin and bake for 22 minutes, or until the cake is lightly golden and springs back when touched.