Preheat oven to 350°F (177°C) and line a baking sheet with parchment
Whisk together the brown rice flour, sorghum flour, tapioca, psyllium, baking powder, and salt.
In a small bowl, add the sugar and work in the orange zest with your fingers.
In a medium bowl whisk eggs, add melted butter, sugar, and zest.
Add the dry ingredients, mix until a dough forms and fold in pistachios and white chocolate.
Drop the dough onto the baking sheet and shape into a 10–11 inch log, about 2 1/2 – 3 inches wide.
Wet hands help smooth the surface.
Bake 25–28 minutes, until the top feels set and lightly golden.
Cool 20 minutes or chill in the fridge (important for clean slices!).
Use a serrated knife to cut into ¾-inch slices. Lay slices cut-side down.
Reduce oven temperature to 325°F (163℃) and bake for 10 minutes, flip, and bake 10–12 minutes more, until dry and crisp.
When fully cool, dip one end in melted dark chocolate.
Let set at room temp or refrigerate 5 minutes before enjoying. these are even better the next day.