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Well, I tried using cornstarch as flour in my favorite brownies recipe.
It didn't work, for a very intersting reason.  It was too light.  The
brownies developed a wonderful crust which separated from the rest of
the batter.

It does lead me to believe that cornstarch must be used as a cake flour
(as Julia Child said), or at least not be used in brownies.

I did find Nick Malgeri's great big new cookbook on baking and I noticed
he has many recilpes for cakes & cookies using either cornstarch, cake
flour or flourless.

I will keep trying my old recipes and let you know the outcome.
Ann