Preheat your oven to 500 degrees.
Using your fingers, work the shortening in with the flour in a large bowl until the flour appears crumbly, about the size of little peas. Stir in the buttermilk with a wooden spoon. Lightly dust your counter top with flour.
Pat the dough down into a neat rectangle – no reason to do any kneading really. Using a pizza cutter, slice the biscuits into 8 squares. Lightly dust your hands with flour, and flatten each biscuit. Press them into each muffin cup. Bake at 500 degrees for 10-12 minutes.
Meanwhile, make the sausage gravy. Brown the sausage in a large skillet until done. Using a slotted spoon, transfer the sausage to a paper towel lined plate. Turn the heat to medium, and add in 1 tablespoon of butter. Melt. Whisk in 1/4 cup of flour, & let cook for 1 minute. Slowly whisk in the milk, a little at a time, and cook until thickened.
Spoon the sausage gravy into the biscuits, making a mound of gravy in the middle. Return to the oven on 500 degrees for an additional 3 minutes. Serve with a sprinkling of red pepper flakes if desired.