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Summary of question on how to use corn starch to bake cookies - ones I
baked using 1:1 substitution were 'dry' and somewhat 'crumbly' -  (long)

- Nancy

Usethe  Betty Hagman g/f flour mix of white rice flour, tapioca starch
and potato  starch - also add xantham gum ( about 1 tsp per cup of flour
mix used).

You need a blend of flour (rice flour) and corn starch because the
starch will be dry. Zanthum gum probably won't help cookies.

I am working on this problem and just emailed Argo cornstarch co for an
answer...will post when I find out.  In the meantime...check out
Brasilian recipes....their cookies are made with cornstarch (use a
search engine---the one Maria somehting or other has some great recipes).

Have been experimenting with " Sweet rice flour " with some success. It
is also called " Glutenous Rice " do  not  let the term scare you. It
seems to be less grainy and does much better in some baking.

Xanthan will help, but working with cornstarch requires more moisture
also.

Use a mix of 3/4c. white or brown rice flour and 1/4 c. sweet rice
flour.   Substitute this in equal amounts for wheat flour (minus 1 or 2
Tb.).

If you use to much of the Zantham Gum cookies will be too rubbery. The
Zantham Gum does help hold them together.

Try  sorghum or Garfava (Chic Pea) flour in place of regular  flour in a
1-1 ratio. Both of these flours "act" more like wheat flour when it
comes to baking. Sorghum even rises like wheat flour.  Add a little
Xanthan gum about 1 tsp. per cup of flour.

Add 1/2 tsp xanthan gum per cup of flour and use potato starch in
combination with cornstarch - equal amounts of the same.