Combine flour, baking powder, sugar, and salt; stir well. Cut in shortening until mixture resembles coarse meal. Combine milk and egg, beating well. Pour milk mixture evenly over flour mixture, stirring until dry ingredients are moistened.
Turn dough out onto a floured surface; knead 10 to 12 times.
Roll dough to 1/4-inch thickness; cut with a 1 1/2-inch biscuit cutter. Spread biscuits with softened butter; make a crease with a knife across each circle and fold in half. Press edges to seal. Place on greased baking sheets. Bake at 450° for 10 minutes or until biscuits are lightly browned.