Preheat your oven to 400 deg F (~205 deg C). Line your baking sheet with parchment paper.
Combine flours, sugar, baking powder, and salt in a bowl. Using a pastry blender or your fingertips, cut the butter into your dry mixture until it resembles coarse breadcrumbs. Stir in your hazelnuts with a rubber spatula.
In a separate bowl, combine the buttermilk and vanilla. Gradually add this to your dry mixture until it comes together as a lightly moist dough.
Turn the dough out onto a lightly floured surface, and knead gently for a minute or two until it comes together. Be careful not to over-mix, or your scones will be dense.
If you want your scones in wedges, divide your dough into two, and pat each to a flat round about 1/2 inch (1.25 cm) thick. Cut each round into 6 wedges with a floured knife or metal bench knife. *Ensure you cut straight down, do not shift the knife back and forth, or this can affect your rise. If you want your scones in rounds, pat your dough down to 1/2 inch (1.25cm) thick, and use a biscuit cutter to cut your biscuits out. If you'd like to glaze the scones, skip this step. Otherwise, brush the tops with heavy cream and sprinkle with coarse sugar.
Arrange your scones 1 inch (2.5 cm) apart on your baking sheet. Bake until golden and cooked through. Wedges will take 18-25 minutes, rounds will take 14-18 minutes, depending on the size of your round. If you touch the center top, and it doesn't dent easily, they are done. If you are not glazing the top, enjoy these warm with maple butter!
If glazing, transfer the scones onto a wire rack set over a parchment lined baking sheet, until they are no longer hot (lightly warm is ok).