In a large mixing bowl, whisk together the flour, sugar, and baking powder.
In a separate bowl, lightly beat the egg yolks. Mix in the milk, melted butter, and vanilla extract until well combined.
Pour the wet ingredients into the dry ingredients, stirring just until the mixture is combined. Do not overmix.
In another bowl, beat the egg whites with an electric mixer until stiff peaks form. Gently fold the egg whites into the batter.