Step 1: In a large food processor, combine the Graham flour, all-purpose flour, brown sugar, baking soda, salt, and cinnamon. Pulse until well mixed.
Step 2: Add the cold, cubed butter to the processor and pulse until the mixture resembles coarse crumbs with no large chunks of butter remaining.
Step 3: In a small bowl, whisk together the honey, milk, and vanilla extract. Drizzle this mixture into the food processor while pulsing until a sticky dough forms.
Step 4: Turn the dough out onto a piece of plastic wrap, pat it into a flat rectangle, and wrap tightly. Refrigerate for at least 2 hours or overnight.
Step 5: Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.
Step 6: On a floured surface, roll the dough to 1/8-inch thickness. Cut into 3-inch squares and place on the baking sheets.
Step 7: Use a fork to prick holes in the surface of each cracker and bake for 13-15 minutes until the edges are golden brown. Let cool completely on a wire rack to ensure maximum crispness.