Preheat the oven to 350°F. Grease a deep 9×9-inch baking pan with baking spray or butter and set aside.
In a large bowl, stir together the flour, baking powder and salt.
In a separate large bowl, beat together the egg yolks and granulated sugar until the yolks are pale yellow in color. Add the vanilla extract and whole milk then beat til combined
Pour the mixture into the large bowl of flour and mix together until combined
In a stand mixer, beat the egg whites on high speed until soft peaks form.
Add the egg whites to the batter and fold together gently until just combined and no white streaks remain.
Pour the cake batter into the prepared pan and bake for 30 to 40 minutes, or until a toothpick inserted into the center comes out clean. Set aside to cool for 20 minutes while you make the three milk mixture.