Heat oven to 425 degrees.
Combine dry ingredients in food processor with steel blade.
Cut butter in small pieces and add to flour mixture and process until mixture resembles a coarse meal. Add buttermilk and process just until dough forms a ball.
Add raisins or cranberries. Pat or roll on a board until dough is about 3/4 inch thick. Cut with biscuit cutter and place on ungreased cookie sheet.