Preheat the oven to 350 F.
Beat egg whites with a hand mixture with one tbsp of sugar (of the ⅓ cup of white sugar) until stiff peaks form.
Gently scrape the beaten egg whites out of the mixing bowl into another medium-sized bowl. Set the whites aside.
In the original mixing bowl, place the egg yolks and the remaining sugar. Turn the mixer on medium-high speed and beat until the sugar is absorbed into the yolks (about 1 minute).
Add vanilla extract, baking powder, and salt. Turn the mixer speed up to high and continue to beat for 8 to 10 minutes on medium speed, or until the mixture is pale yellow, thick, and nearly tripled in volume. Don’t skimp on this step!
Remove the bowl from your stand mixer and add around ¼ of the whipped egg whites. Folding in this small amount first will loosen up the batter. Add the remaining egg whites and carefully fold them in.
Using a sifter, sift ⅓ of the flour at a time over the egg white mixture, and with a flexible rubber spatula or whisk, start folding the flour into the wet ingredients. Make sure to combine everything and there are no pockets of flour.