Preheat oven to 475°. Grease cast iron pan.
In a medium mixing bowl, stir together flour, baking powder and salt. Use scoop and sweep method to measure flour.
Using a pastry cutter, cut in shortening until mixture resembles coarse crumbs.
Make a well in the center and pour in all the milk.
Using a fork, stir together the ingredients just until the dough starts to come together and begins to pull away from the sides of the bowl. Dough will be sticky.
Turn dough out of the bowl onto a lightly floured surface.
With floured hands, lightly knead the dough for about 30 seconds, until nearly smooth.
Using a lightly floured rolling pin, roll out the dough to ¾ inch thickness.
Cut dough with a 2 ½ inch biscuit cutter. Dip the cutter in flour, in between cutting each biscuit. Press down but do not twist biscuit cutter.
Place biscuits close together, but not touching in a lightly greased cast iron pan.
Brush tops with melted butter.
Bake in a 475° oven for 11-15 minutes or until biscuits are golden brown.
Serve warm with butter.