In a bowl, combine the flour, bran and wheat germ, baking powder, baking soda, salt and cinnamon. Reserve.
In another bowl, combine honey, milk and vanilla. Reserve.
In another bowl, cream the butter with the brown sugar with an electric mixer. At low speed, add the dry ingredients alternately with the milk mixture until the preparation is homogeneous. Shape three discs with your hands. Cover with plastic wrap and refrigerate for about 1 hour.
Place the grill at the center of the oven. Preheat the oven to 180 ° C (350 ° F). Line a baking sheet with parchment paper.
On a floured work surface, roll out one piece of dough at a time, into a square about 3 mm (1/8 inch) thick. Using a knife or pizza cutter, cut the dough into 6 cm (2 ¼ in.) Squares. Using a spatula, place the squares on the baking sheet.
Using a fork, prick each square several times. Bake for about 12 minutes or until the cookies are golden. Let cool. Repeat with the rest of the dough. Reuse scraps.
