Because we’re using buttermilk and a liquid sweetener for these scones, this dough is definitely on the wet side — so do know you’ll want to use some flour to help you form it into a disk without sticking to the counter … and your hands. And don’t skip the step where you let the dough rest for 10 minutes — that’ll help the whole-grain flours soak up a little of the moisture. If you have trouble finding whole-wheat pastry flour, feel free to use spelt flour or all-purpose flour instead.
Preheat the oven to 350 F. Lay the walnuts on a small baking sheet and toast until fragrant, about 8 minutes. Set aside to cool. In the bowl of a food processor, pulse 1 cup of the walnuts until very finely ground. Coarsely chop the remaining 2 cups.
Increase the oven temperature to 375 F. In a medium bowl, whisk together the flours, baking powder, baking soda, salt and cinnamon. Whisk in the ground walnut meal. Add the cubed butter and, using your hands or a pastry cutter, rub or cut the butter into the flour mixture until it resembles small, course peas. Do this quickly so the butter won’t warm too much. It’s o.k. to have a few larger chunks of butter. Fold in the remaining chopped walnuts.
In a small bowl, whisk together the buttermilk, maple syrup and vanilla extract. Add to the dry ingredients and, using a wooden spoon or flat spatula, stir until the dough gathers together (I actually use my hands at this point). The dough will be pretty wet and that’s o.k. Let it sit for 10 minutes to allow the whole-grain flours to soak up a bit of the moisture.
Take out a large wooden board (or use a clean table surface) and sprinkle generously with flour. Turn the dough out onto a well-floured counter or surface and sprinkle the top with a little flour. Gather the dough into a ball and pat/push it down so it’s circular in shape and about 1-inch thick. Cut into 6 large wedges (or 8 for smaller-size scones).
Place the wedges on an ungreased baking sheet, brush the tops with buttermilk and sprinkle with a little sugar. Bake for about 25-30 minutes – or until tops are lightly brown. Cool on the pan for five minutes before transferring to a rack to cool completely.