Heat the oven to 450 degrees. Mix the dry ingredients together in a food processor. Cut the butter into bits and pulse it in the food processor until thoroughly blended.
Using a large spoon, stir in the yogurt until mixture just forms a ball. turn dough out onto a lightly floured surface and knead it 10 times; no more. If it is sticky, add a little flour, but very little; it should still stick slightly to your hands.
Press the dough into a 3/4 inch thick rectangle and cut into 2-inch rounds. Put on ungreased baking sheet. Gently reshape the leftover dough and cut again. Bake for 7 - 9 minutes or until the biscuits are a beautiful golden brown. Serve within 15 minutes for them to be at their best.