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Got questions from several new people about using cornstarch in place of
cake flour.  Julis Child, in one of her first books, recommends this.
Use it one to one.  A cup of cake flour - a cup of cornstarch.  No
changes need be made to recipe.  It acts and tastes the same.  One
slight difference is that the cornstarch gives a more delicate crumb, so
wait until cake is totally cooled before cutting.  It has a tendecy to
dry out more  quickly [if it lasts that long], so keep it well wrapped.

I had asked a professional baker about this substition, did he know
about it, did it work, etc?  He said it worked just fine.  Another pt he
made was that as far as cakes were concerned, cake flour and ap flour
are interchangeable.  There fore, in cakes at least [and bar cookies
such as brownies], you can use cornstarch, measure for measure for all
purpose flour.

I prefer the cornstarch over the other alternative flours because it is
light, does not have that grittiness and if virtually indistinguishable
from wheat flour in these recipes.  My daughter and her frieds did a
side by side taste test for me with my usual brownie recipe and not only
could they not tell the difference, they preferred the brownies made
with cornstarch!

Ann