Preheat oven to 425 degrees Fahrenheit. Sift all dry ingredients into mixing bowl, then transfer into food processor. Cut butter and lard into thirds. Add 1/3 of the butter and lard to food processor and pulse until incorporated. Repeat this addition in two more batches, pulsing until completely combined and flour looks similar to sand. Transfer mixture back to mixing bowl and add buttermilk. Using either a clean hand or fork, incorporate the buttermilk into the flour mixture. Once fairly mixed, transfer to a counter surface coated with flour. Pat clean hands with flour and sprinkle over the top of the dough. The dough will be sticky. Form into a ball, coating hands with flour and dusting when needed. Do not overdo the flour. Divide dough into equal portions, close to the size of an egg or a baseball. One by one, roll in between your hands to form a complete ball, and transfer to an ungreased, but seasoned, cast iron skillet. Place skillet into preheated oven for 20-25 minutes, or until biscuit tops are golden brown. Brush with melted butter.
Cook the breakfast sausage in a skillet until golden brown. Remove sausage from skillet, leaving the grease in the pan. If the sausage did not render enough liquid to cover to cover the bottom of the skillet, add the additional butter or bacon grease and allow to melt completely. Once the grease is bubbling, sprinkle the flour over the top, making sure not to dump or spill into the skillet as this may cause lumps. Using a whisk, constantly and quickly whisk the roux until golden, making sure to scrape any bits from the bottom of the pan. Once golden in color, slowly start adding the room temperature milk, a small amount at a time. Continue to whisk until it thickens, adding the milk in stages until it is slightly thick. Sauce will thicken as it continues to cook, and also as it cools. Add sausage, a generous amount of fresh cracked pepper, a pinch of salt, and hot sauce to taste. Pour over freshly baked biscuits. Serve immediately.