Preheat oven to 350 degrees and line 2 baking sheets with silicon mats or parchment paper.

Add the shortening and granulated sugar to the bowl of a stand mixer and beat on medium-low speed until just combined. Scrape down the bowl as necessary. Add the egg and vanilla extract and mix until combined.

In a medium bowl, sift and whisk together the flour, cocoa powder, salt, and xanthan gum. Pour 2/3 of the flour mixture into the wet ingredients and mix on low speed until mostly combined. Scrape down the bowl and add the remaining flour and mix until just combined and the dough starts to come together.

Form the dough into one large ball and split in half. Place half of the dough on a large piece of plastic wrap and top with a second piece of plastic wrap. You do not need to dust it with flour. (Keep the other half covered with plastic wrap to keep from drying out in the bowl.)

Roll the dough out between the layers of plastic wrap to 1/4 inch thick. Cut with desired cookie cutters. Dough scraps can be re-rolled. Carefully place the cookie shapes on the prepared baking sheets and bake at 350 degrees for 8-10 minutes. Bake the cookies in batches as necessary.

Cool cookies on the baking sheet for at least 15 minutes before very carefully transferring to a wire rack to cool completely. When warm out of the oven, the cookies will be extremely delicate (to the point where they will crumble if you touch them and you'll think they're going to be a crumbly mess) but will be firm and sturdy once they have cooled.

Decorate as desired once completely cooled.