Should we make our own aqua faba, or is there a store we can buy it from? Also: where can one find Xanthan gum? I'm eager to try this yummy recipe!

You can get Xanthan at Whole Foods.

Thanks, Lori and Smaug, for the helpful information; I'll be making my shopping list now!

You get aqua faba inside every can of chickpeas, and every time you cook up a pot of chickpeas as well. It's just the liquid left behind after they cook. You can buy it separately, but it's simple enough to get otherwise. A can of chickpeas usually contains plenty for most purposes and you can always find a use for the cooked beans themselves. If you are in the US, finding xanthan gum may be as simple to do as visiting a local grocery store, health food store, or natural foods store. Since gluten free baking has become such a thing, lots of these places have established sections for doing just that and carry a variety of the items necessary. You can also order it from Amazon, or directly from Bob's Red Mill.

I'm pretty sure Bob's Red Mill has Xanthan gum- they have a lot of outlets but also a huge product line, so you might have to look around. Then there's always Amazon.