Preheat your oven to 350 F and butter a square 8-inch pan (if you like a thicker slice) or a 9x13 baking pan if you like the thickness in the pictures.
Separate the yolks from the whites. In the yolks, add half of the sugar and whip it up with your mixer until its pale yellow, fluffy and has tripled in volume. Add vanilla extract and mix. The batter should fall in a ribbon.
In another bowl, whip up the whites with the remaining sugar (add it all at once) until stiff peaks form. This will take some time.
In a bowl, combine the flour with the baking powder and salt and sift half of it into the bowl with the egg yolks. Using a spatula, fold the flour into the egg yolks and add pour in milk slowly to help it combine. Once the flour has incorporated completely, fold in the egg whites very carefully so as not to deflate the batter. When folding, I scoop the batter and drop it in itself until all of the whites have been added and fully incorporated into the batter. Do not use a whisk.
Pour the batter into the prepared pan and bake for 20 mins or until the top becomes golden brown and a skewer inserted into the center of the cake comes out clean. My oven baked these super fast (about 12-15 mins) so just keep an eye out on your oven.
Once baked, let the cake cool slightly and then poke it all over with a fork.