Lightly spoon the flour into the dry measuring cup and level with a knife. Combine the flour with the baking powder, baking soda and salt in a large bowl and stir to combine.
Next cut in the vegetable shortening with a pastry cutter, fork or two knives until it resembles a fine crumb.
Add the buttermilk and stir until just moist.
Turn the dough out onto a well floured surface (it will be sticky) and knead it lightly five times.
Pat the dough into a rectangle of 1/2" thickness. Cut with a large, round cookie cutter or slice with a knife into 6 biscuits.
Place on a baking pan prepared with non stick cooking spray and bake for 10 minutes at 450°F or until golden brown.
Crumble and then brown the sausage over medium-high heat until fully cooked. Reduce the heat to medium-low. Sprinkle the flour over the sausage and stir until the sausage soaks up the flour. The meat will look very dry.
Turn up heat to medium-high and pour in the milk. Add the pepper and salt, to taste. Stir until gravy is very thick, about 10 minutes. If the gravy gets too thick, add a little more milk to thin it to your desired consistency. Serve atop biscuits