Mocha-Pistachio Biscotti

Preheat oven to 350 °. Weigh or lightly spoon flours and cornstarch into dry measuring cups; level with a knife. Combine flours, cornstarch, cocoa, and next 5 ingredients (through salt) in a medium bowl; stir with a whisk. Beat brown sugar, granulated sugar, coffee granules, vanilla, and eggs with a stand mixer at medium speed until well blended. Gradually add flour mixture; beat until blended. Add pistachios; beat on low until blended. Turn dough out onto a lightly floured surface; divide dough in half. Shape each half of dough into a 12-inch-long roll on a baking sheet lined with parchment paper; pat to a 3/4-inch thickness. (Flour hands with brown rice flour if dough is sticky.) Bake at 350 ° for 20 minutes or until firm to touch. Remove rolls from baking sheets; cool 30 minutes on a wire rack. Cut each roll diagonally into 20 (1/2-inch) slices Place slices on baking sheets, and bake at 350 ° for 6 to 8 minutes. Turn slices over and bake an additional 6 to 8 minutes (cookies will be slightly soft in center but will harden as they cool). Remove from baking sheets; cool completely on wire rack.