The combination of roasted sweet potatoes and sage gives these scones a sweet and savory flavor profile that makes them a delicious treat for breakfast or dessert.
Sift together flour, sugar, salt, baking powder, and nutmeg in a medium bowl. Cut cubed butter into the flour mixture with a fork or pastry blender until it is crumbly and coarse, and then stir in chopped fresh sage.
In separate bowl, mix mashed sweet potato, buttermilk and 2 tablespoons of the heavy cream. Make a well in the center of the flour mixture, and add sweet potato mixture. Quickly stir mixture together until a ragged dough forms.
Sprinkle a clean counter top or work surface with flour. Turn the dough out onto the prepared work surface and knead briefly. Shape the dough into a 7-8 inch round and cut into 8 wedges.
Transfer to a parchment lined baking sheet, making sure wedges are separated by at least an inch. Brush the remaining 1 tablespoons of cream evenly onto the wedges. Sprinkle tops of wedges with coarse crystal sugar. Bake on middle rack until bottoms are golden brown, 30 to 35 minutes. Let cool on baking sheet until ready to serve. Garnish with individual sage leaves if desired.