In a bowl, whisk together the powdered sugar and xanthan gum or guar gum. Add the water, a little at a time, stirring until it incorporates and forms "dough."
Knead the "dough" a few times. Roll it out with a rolling pin. Cover the rolled dough with plastic wrap and let it rest for about 15 minutes.
Cut a circle out of the "dough" that's about 1½ inches in diameter, and cover the remaining "dough" in plastic wrap. Roll out the circle until is very thin. Repeat this step with the remaining fondant "dough."
Ghost Cookies
Take 1 cookie and roll it in your hands until it is a round ball.
Take fondant circle and drape it over the cookie. Place 2 chocolate chips for the eyes.
Serve immediately. These ghost cookies may be stored covered tightly in plastic wrap (to keep from drying out) for up to 2 days.
Notes
Fondant Flavors: You can use clear extracts to flavor the fondant. Clear vanilla extract is readily available, and LorAnn's Super Strength Flavors are fun and allergy-friendly. Add the extract with the water to avoid adding too much moisture.
Recipe by Go Dairy Free at https://www.godairyfree.org/recipes/ghost-cookies