This recipe is originally adapted from RaisingJane.org, a Mary Jane's Farm blog. 1 1/4 cups tapioca flour, plus more for dusting1. Preheat oven to 325°F. Line three large baking sheets with silicone baking mats or parchment paper. 2. In a large bowl or food processor, combine brown rice flour, tapioca flour, brown sugar, baking powder, salt, and xanthan gum. Cut in butter until mixture resembles course crumbs. 5. Lightly dust a clean work surface with tapioca flour.