Preheat oven to 350° and grease a 9 x 13" baking pan with non stick cooking spray.
In a large bowl whisk together flour, baking powder, and salt.
Separate eggs and egg yolks.
In a second large bowl beat together egg yolks and 1 cup of sugar. You want the mixture to be stiff but dry. Then beat in vanilla and set aside.
In a third large bowl using a hand mixer, beat egg whites until soft peaks form.
Add dry ingredients to yolk mixture and beat together. Once combined, add in milk and melted butter and beat until combined. Gently fold in egg whites until all is combined.
Pour batter into greased pan. This will be a more shallow cake than many!
Bake until a toothpick inserted into middle of cake comes out clean. This took exactly 30 minutes.