Preheat the over to 325. Prepare two baking sheets with parchment paper

In a food processor, grind the walnuts very fine. They may get pasty, but that is ok

In a large bowl cream together the shortening, nuts and vanilla using a large spatula

Add in the granulated sugar

Sift the gluten free flour and xanthan gum into the bowl and mix with the spatula until well incorporated

Layout a large piece of wax paper on the counter and start to spoon out mounds of dough, about a tablespoon each. You will end up with about 40 cookies

Form each mound into a crescent: The best method is to roll the mound into a short fat log with the heel of your hand against the wax paper (to minimize heat). Then use your fingers to shape the cookie into a crescent shape, bending in the edges and tapering the ends a bit. Carefully transfer to the prepared baking sheet.  Place cookies about one inch apart as they will puff and spread. You can always form round mounds instead for cookies if you're feeling less fancy

Bake in the oven for 18-20 minutes, turning halfway through, until the tips are lightly golden brown. Remove from oven and let cool on the pan for 5 minutes. With a metal spatula, VERY carefully transfer to a cooling rack

When completely cool, dust with powdered sugar