Sift together the flour, baking powder, soda and salt. Place in a mixing bowl.
Add the shortening. Using a wire pastry blender or two forks, quickly cut in the shortening until the mixture resembles very coarse meal. Pour in the milk. Lightly mix just until the milk is mixed in and a soft dough forms.
Generously flour a large board. Turn the dough out onto the board, coating the bottom side. Quickly turn to coat the other side. Pat out with floured hands or gently roll with a floured rolling pin to 1/2 to 3/4" thickness. Cut out with a 2 1/2-3" biscuit cutter. Cut close together using as much dough as possible to prevent reforming and rolling again.
Place the biscuits close together on a lightly greased baking sheet.
a preheated 450º oven for about 10 minutes, or until golden brown.
Makes about 15 biscuits.
Peppered Basil Biscuits: Add 1/2 teaspoon coarsely ground black pepper to the dry ingredients and 1 tablespoon chopped fresh basil leaves along with the buttermilk.