Recipe from Easy Gluten-Free Baking by Elizabeth Barbone, who has the most amazing gluten free baking recipes I have come across.
1 1/2 cups brown rice flour
1/2 cup cornstarch
1/3 cup dark brown sugar
1 teaspoon baking powder
1/2 teaspoon salt
5 tablespoons butter, cold
6 tablespoons milk
3 tablespoons honey
1. Preheat oven to 350°F.
2. In the bowl of a food processor, combine dry ingredients. Pulse to combine. (If you don’t have a food processor, whisk dry ingredients together in a medium mixing bowl.)
3. Add the butter. Pulse until flour mixture is coarse. No large pieces of butter should remain. (Or cut cold butter into flour mixture with a pastry cutter, two knives or by rubbing the butter between your fingers.)
4. Add milk and honey. Pulse until dough forms. (Or stir using a wooden spoon.)
5. Turn dough out onto a lightly rice floured piece of 12×16 parchment paper.
6. Pat dough into a rectangle. Dust the top of the dough lightly with rice flour.
7. Place another piece of 12-by-16-inch parchment paper on top of the dough. Roll dough out until it covers all of the paper. Dough rectangle will be about 1/8 inch thick.
8. Carefully remove top piece of parchment paper.
9. Transfer dough, with bottom parchment paper, to a 12 x 18 baking pan.
10. Using a pizza wheel, score the dough into rectangles. (The rectangles should be 6 x 2 3/4 inches large for “standard” graham crackers and 3 by 2 3/4 for a “s’more” size graham cracker.) The graham crackers will break apart after baking. Do not worry if the dough seems to still be touching after scoring with the pizza wheel.
11. Prick dough all over with a fork. Chill dough for 10 minutes.
12. Bake for 15 minutes or until evenly brown. Remove graham crackers from the pan and place on a wire rack to cool. (slide the parchment, with the crackers, directly onto the cooling rack.) Allow crackers to cool completely. Break along scored lines.