I want to make this gluten-free. What is your advice? I have gluten-free flour and xantham gum. Thanks!!

If you have a gluten-free flour mix such as Thomas Keller's Cup4Cup (which contains cornstarch, white rice flour, brown rice flour, milk powder, tapioca flour, potato starch, xanthan gum) you can just replace the regular all-purpose white flour with an equal amount. If you have a single ingredient gluten-free flour such as millet flour or tapioca starch, you would have to create your own baking blend that would necessitate the use of the xanthan gum. Good luck!