Cake Flour in Black and Whites
 

I noticed that the recipe for Black and Whites calls for equal parts of
flour and cake flour. What is cake flour? I went to the supermarket and I
only found one type of cake flour. When I looked at the incredients, they
are basically the same as flour.

Can something be replaced for cake flour? Maybe baking powder or baking
soda to give it a fluffier texture?

Thanks.