Preheat oven to 350°F. In bowl of a food processor, combine brown rice flour, dark brown sugar, tapioca starch, cocoa powder, baking powder, and salt. Pulse to combine.

Add butter. Pulse until no large pieces of butter remain. Add milk and corn syrup (or honey). Pulse until dough forms.

Turn dough out onto a lightly rice floured piece of 12 x16 parchment paper. Pat dough into rectangle. Dust top of dough lightly with rice flour. Place another piece of 12x16 parchment paper on top of dough. Roll dough out until it covers all of the paper. Dough rectangle will be about 1/8 inch thick.

Using pizza wheel, score dough into rectangles. (The rectangles should be 6 x 2 3/4 inches large for standard graham crackers and 3 x 2 3/4 for a “s’more” size graham cracker.) Prick dough all over with fork. Chill dough for 15 minutes.

Sprinkle granulated sugar lightly over top of dough. Bake until crackers are set, about 15 minutes. Remove graham crackers from pan and place on wire rack to cool. (I slide the parchment, with the crackers, directly onto the cooling rack.)