Preheat oven to 350°F. Spray a 14x11 baking pan.
In a large mixing bowl add the flour, baking powder, and salt then mix together with a spoon.
In two separate bowls, carefully separate the egg yolks and the egg whites. If some egg yolks slip into the egg whites, be sure to take them out. Use a spoon and take them out.
Now, whisk together egg yolks with 1 cup sugar until well incorporated then mix in the milk and vanilla extract.
Pour the egg yolk mixture over the flour mixture. Whisk until well combined.
Using a hand mixer, beat the egg whites on medium-high speed until soft peaks form. Halfway add 1 tablespoon of sugar and continue to beat egg whites on high until peaks are stiff.
Pour the egg whites over the batter then fold using a rubber spatula (don’t whisk or stir) into the batter carefully until well combined.
Pour the batter into a prepared baking pan and spread to even out the surface. Bake for 35 minutes or until a toothpick comes out clean.