Into a medium bowl, sift together graham flour, whole-wheat flour, all-purpose flour, cinnamon, baking powder, baking soda, and salt; set aside.
In the bowl of an electric mixer fitted with the paddle attachment, cream butter and sugar on low speed for 1 minute. Add honey and vanilla, and beat to combine. With the mixer on low speed, add the flour mixture in two additions, alternating with the milk and beginning and ending with the flour.
Divide the dough into thirds, and roll each third to a 1/8-inch thickness between two sheets of parchment paper. Stack the dough on a baking sheet, and freeze for 1 hour.
Preheat oven to 300 degrees. Line baking sheets with Silpats or parchment paper. Remove 1/3 of the dough from freezer. Gently remove top sheet of parchment paper. Flip package onto a prepared baking sheet. Peel off and discard the remaining piece of parchment paper. Cut out cookies using 3-inch alphabet cutters. Transfer cookies to prepared baking sheets. Re-roll and cut any dough scraps between parchment paper. Bake until lightly browned, 20 to 25 minutes. Repeat with remaining dough. Remove cookies to wire racks to cool completely.