These nutty confections look like round snowballs and are a favorite at cookie exchanges. Swap the pecans for skinned hazelnuts or walnuts if your prefer. You can try replacing my AP GF Flour Blend with your own, or a purchased GF Flour, however I can't guarantee the results, as I've only tested the recipe with mine.
Pulse together flour blend, almond flour, xanthan gum if using, sugar and pecans (in the bowl of a food processor fitted with the steel blade) until nuts are finely ground. Add butter and pulse just until large crumbs form. Add the egg and pulse again, just until the dough comes together. Remove dough and wrap in plastic, shaping into a disk. Refrigerate for at least 2 hours.
Preheat the oven to 350 degrees. Shape dough by the tablespoonful into balls and place 1 inch apart on baking sheets. Bake in batches until lightly golden brown, about 15-20 minutes per batch.
While cookies bake, lightly sift a layer of powdered sugar onto a baking pan with sides. When cookies are finished baking, transfer them to the sugared pan, and sprinkle additional sugar on top of each cookie. Transfer cookies to a rack to cool completely.