Preheat oven to 400 degrees.
Transfer mixture to large bowl. Add 1 cup buttermilk, stirring quickly to combine. If mixture is too dry, add more buttermilk, 1 tablespoon at a time, until dough holds together and is slightly stringy and crumbly. Turn out onto lightly floured surface. Knead 6 to 7 times (do not knead more than that or scones will become tough).
Divide dough in half. With floured hands, press each half into 9x4-inch rectangle. With short side facing you, fold into thirds like a business letter. Press each portion into 6 to 7-inch circle; place on ungreased baking sheet. Cut each circle into 6 equal wedges; pull wedges slightly apart. Brush tops with remaining buttermilk. Let stand 10 minutes.