I am making Molly Yeh's pistachio loaf cake, and it calls for xanthan gum. I realized the GF flour that I have at home is King Arthur's and it doesn't contain xanthan gum. I don't have much experience with GF baking; what happens if I omit it from the recipe? And where can I get it in small quantities?
(Oh, and $10 off your order of $50 or more in the Food52 Shop, too.)