Preheat waffle iron to medium.

In the bowl of an electric mixer, beat egg whites until soft, glossy peaks form.

In another bowl, whisk the flour, sugar, baking powder and salt.

In another bowl, whisk the egg yolks, milk, butter, oil and vanilla extract.

Mix the wet and dry ingredients together.

Next, carefully fold in the egg whites.

Using a ladle, ladle the batter into the waffle iron and cook until desired doneness, about 4 minutes for golden waffles.