Heat a large cast-iron skillet over medium-high heat. Add sausage. Break it up with a spatula or wooden spoon and cook stirring occasionally, until well browned and cooked through. About 8 minutes. Remove excess grease with a small ladle, leave about 2 tablespoons in the pan with the meat.
Dust flour over the sausage and stir it into the meat, then pour the milk into the skillet and continue to stir, bringing the gravy to a boil. Lower the heat and simmer gently for about 5 minutes. Season with black pepper to taste.