1/2 cup (113 grams) unsalted butter, cold and cut into pieces
2/3 - 3/4 cup (160 - 180 ml) buttermilk
1 teaspoon vanilla extract (optional)
Preheat oven to 400 degrees F (200 degrees C) and place oven rack in middle of oven. Line a baking sheet with parchment paper. In a large bowl, whisk together the flour, sugar, baking powder, baking soda and salt. Cut the butter into small pieces and blend into the flour mixture with a pastry blender or two knives. The mixture should look like coarse crumbs. Add the buttermilk and vanilla extract to the flour mixture and stir just until the dough comes together. Do not over mix.
Transfer the dough to a lightly floured surface and knead the dough gently and form into a 7 inch (18 cm) round that is about 1 inch (2.5 cm) thick. Use a 2 1/2 inch (6.5 cm) round biscuit cutter to cut the dough into circles. Transfer the scones to the baking sheet and brush the tops of the scones with a little milk.
Bake for about 18-20 minutes or until golden brown and a toothpick inserted in the middle comes out clean. Remove from oven and transfer to a wire rack to cool. Can be stored at room temperature for a few days.
Makes about 10 - 2 1/2 inch (6.5 cm) or 8 wedge-shaped scones.