In a stand mixer, beat the butter and brown sugar together on medium speed for 3–5 minutes, until the mixture lightens in color and becomes fluffy.113 grams unsalted butter, room temperature, 145 grams brown sugar
Mix in the honey, vanilla, and sourdough discard until fully combined.80 grams honey, 10 grams vanilla extract, 120 grams sourdough discard
Add the flours, cinnamon, baking soda, and salt. Mix until a dough forms.210 grams whole wheat flour, 70 grams all-purpose flour, 2 grams cinnamon, 5 grams baking soda, 5 grams salt
Dump the dough onto plastic wrap and then wrap it up loosely. Press down on the dough to flatten it into a square or rectangle and place it in the fridge for at least 1 hour.
Preheat the oven to 350°F.
Divide the chilled dough in half. Place half the dough on a floured surface and flour the top of the dough along with the rolling pin. Roll out the dough thinly into a large rectangle—about 1/16 inch thick. The dough should lift easily from the counter; if it sticks, flour both the dough and your rolling pin.
Use a pizza cutter or sharp knife to cut the dough into rectangles. For standard store-bought graham cracker size, cut them to 2¼ x 4¾ inches. Poke 5-7 holes down the center of each cracker using a fork. If you'd like clean, straight edges, trim the outer edges of the dough first—then gather and re-roll the scraps to cut additional crackers. Repeat with the remaining half of the dough.
Transfer the crackers to a lined baking sheet, spacing them so they don’t touch (about 10 per sheet). Bake for 13–15 minutes, or until lightly golden. The crackers will still feel soft out of the oven but will crisp up as they cool.
Place on a cooling rack to cool.
Notes
Baking on parchment paper will bake the crackers a little quicker than silicone mats will. Also if the crackers are thicker they may take a little longer to bake.
Be sure to roll out the dough thin and evenly. If the graham crackers are too thick, they won't be as crispy.
If the dough is sticky, add extra flour when rolling to prevent it from sticking to the work surface and rolling pin and to help make the dough easier to work with. If it is really soft and sticky when rolling it out simply knead a little flour into the dough and then roll it out again on a floured surface.
For straight, even lines, cut against the edge of a ruler.