Sift together dry ingredients. Cut in shortening with pastry blender until mixture resembles coarse meal. Sprinkle buttermilk evenly over flour mixture, stirring until dry ingredients are moistened. Turn dough out onto a lightly floured surface; knead 3 to 5 times until smooth.
Roll dough out to 1/2-inch thickness; cut with a 2 1/2-inch biscuit cutter. Place biscuits on a lightly greased baking sheet. Bake at 450° for 10 to 12 minutes or until lightly browned.