Step 1

Place a rack in middle of oven; preheat to 350°. Toast cashews on a rimmed baking sheet, tossing halfway through, until golden, 8–10 minutes. Let cool before chopping into pea-size pieces.

Step 2

Beat butter and brown sugar in the bowl of a stand mixer fitted with the paddle attachment on medium speed until light and fluffy, about 5 minutes. Add egg and vanilla and beat 1 minute. Add sorghum flour, all-purpose flour, baking soda, baking powder, and salt and beat just until combined. Add cashews, coconut, and toffee. Mix just until combined. The dough will be very soft at this point. Wrap tightly and chill at least 30 minutes or up to 2 days (if chilling for more than 30 minutes, transfer to a sheet of parchment paper or plastic wrap, flatten into a disk, and wrap tightly to prevent drying).

Step 3

Place racks in upper and lower thirds of oven; preheat to 375°. Divide dough into 16 equal portions (about 1½ oz.; 45 g each). Working quickly so that the dough doesn’t warm up, roll each portion into a ball with your hands. Divide cookies between 2 parchment-lined baking sheets, spacing at least 3" apart. Press gently with palm of your hand to flatten and decorate with a sprinkle of shredded coconut.

Step 4

Bake cookies, rotating baking sheets top to bottom and front to back halfway through, until edges are brown but centers are still a little gooey, 12–14 minutes. Let cookies cool on baking sheets before serving.Do ahead: Dough can be formed into balls 2 weeks ahead; freeze on a baking sheet until solid. Transfer to an airtight container or freezer bags and keep frozen. Bake from frozen; cookies may take a few minutes longer to bake. Cookies can be baked 2 days ahead; store airtight at room temperature.