Preheat the oven to 425 degrees F (212 degrees C). Grease a cookie sheet.
In a medium bowl, stir together the oat flour, bran, salt, baking powder, cream of tartar, cinnamon and sugar. Cut in the butter until the mixture resembles coarse crumbs. Stir in the egg, milk and vanilla until mixture is well blended.
Drop by heaping tablespoonfuls onto the prepared cookie sheet. Bake for 12 to 15 minutes in the preheated oven, cookies should be lightly browned.
