So I found a Yellow cake recipe (http://www.marthastewart.com/342396/yellow-butter-cake) and it calls for both cake and all-purpose flour. I don't have cake flour so I am wondering if I can just use all purpose flour for the recipe or should I use both? Thanks for your input.
Just use the AP flour. Take out 2TBS per cup of cake flour required by the recipe. This is a standard substitution for cake flour.