Mill the soft white wheat berries on the finest setting.
Whisk together the freshly milled flour, pumpkin pie spice, cinnamon, cream of tartar, baking soda, and salt.
In a separate bowl, cream together the softened butter, brown sugar, and granulated sugar until creamy.
Mix in the pumpkin puree, egg, and vanilla.
Add the dry ingredients to the wet ingredients and mix just until combined.
Cover and refrigerate the cookie dough for at least 1 hour.
Preheat the oven to 375°F and line a baking sheet with parchment paper.
Mix together the sugar, cinnamon, and pumpkin pie spice for the coating.
Using a 1½-inch cookie scoop or heaping tablespoon, scoop the chilled dough and roll each ball generously in the pumpkin-cinnamon sugar mixture.
Place on the prepared baking sheet, leaving several inches between each cookie.
Bake at 375°F for 8–10 minutes. Bake 8 minutes for softer cookies or closer to 10 minutes for a slightly crispier bottom.
Transfer the cookies to a wire cooling rack to cool completely.