Preheat oven to 450 degrees F. In a large bowl mixing bowl, combine flour, sugar, baking powder, baking soda, salt and cayenne pepper. Cut in shortening with a pastry blender or two forks until crumbly. Gradually add milk, stirring just until dry ingredients are moistened. Dough should be sticky. Do not overwork dough.
On a lightly floured surface, roll dough to 1/2-inch thickness with a floured rolling pin. Cut 12 biscuits with a 2 1/2-inch round biscuit cutter. Place biscuits in a cast iron skillet or hoecake pan that has been sprayed with a non-stick spray and brush tops with half of melted butter. Bake for 12 to 14 minutes, or until lightly browned. Brush with remaining melted butter before serving.
While biscuits are baking, start gravy. In in large saute pan or cast iron skillet, cook sausage over medium-high heat until browned and crumbly. Reduce heat to medium and add flour to sausage; mix thoroughly. Cook until flour browns, about 4 minutes stirring constantly. Add milk slowly and increase heat to medium-high. Continue to stir. Add hot sauce, pepper and salt. As the gravy comes to a boil, it will thicken. If too thick, add additional milk. After boiling, reduce heat to a simmer and add butter.
To serve place two of the buttermilk biscuits on each plate and top with sausage gravy and garnish with freshly cracked pepper.