Heat oven to 375°F/190℃.
Line 2-3 sheet pans with parchment paper. Set aside.
In a large bowl, whisk together whole wheat flour, all purpose flour, oat flour, wheat germ, brown sugar, salt, baking powder, and baking soda.
Grate butter into flour mixture.
Toss gently to coat.
Add water, honey, and vanilla.
Mix until dry ingredients are fully incorporated and dough is smooth.
Working with half the dough at a time, roll out into a rectangle that is ⅛" thick.
Use a 4 ½ inch x 3 inch cutter to cut out rectangles.
Place on prepared pan.
Repeat with remaining dough.
Use a fork to prick dough.
Bake for 12-14 minutes, until light brown.