Put the flours, salt, baking powder, baking soda, and sugars into the bowl of a processor and pulse to combine.
Add the cold butter and pulse about 30 times until the large chunks of butter are incorporated and the mix is grainy.
In a liquid measuring cup beat the egg, and then add the maple syrup, and extracts. Then add enough cold buttermilk to bring the liquid up to 1 cup.
Add the walnuts to the processor, and then, while you are pulsing the machine, pour the liquid into the dry just until it starts to come together. You may not need all the liquid.
Transfer the dough to a floured surface and bring together into an 8 inch disk. If it is VERY wet, knead in a little more flour until it comes together. Cut the disk into 6-8 scones and lay them carefully on a silicone or parchment lined baking sheet. The dough will be wet, almost like a drop biscuit consistency.
Put the tray in the refrigerator or freezer, if possible, for 15 minutes, while you clean up.
Bake for about 15 minutes for 8 scones, and 18-20 minutes for 6 scones, until firm on top and lightly browned. Cool them on a rack while you make the glaze.
Stir or whisk together the powdered sugar, the maple syrup, and extract, beating until smooth and glossy. Add more syrup if it's too thick, or a little more sugar if it's too thin.
Spread a layer of glaze on each cooled scone and top with crushed walnuts.
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