Sift the flour and baking powder into a large bowl. Using your fingers, rub in the butter until the mixture resembles a crumbly texture. Add the yogurt all at once and mix briefly to form a soft dough.
On a lightly floured surface, roll the dough out to 1 inch in thickness. Dip a 3-inch cutter into some flour, and stamp out 12 scones. (You may have to re-roll the dough to get 12.) Place scones 2 inches apart onto baking sheets. Brush tops with milk.
Bake in preheated oven for 10 minutes or until risen and golden brown. Best served freshly baked with butter.
