When the sausage is done, we remove them from the pan and put them on a paper-towel lined plate. We then keep the sausages warm in a glass pie plate in the oven while we start to make the gravy.
The sausage released about 3 tablespoons of fat. We add the flour, lower the heat to medium-low, and cook the flour for about 4 minutes stirring constantly with our flat whisk.
Meanwhile, we heat the milk in the microwave for a minute. We add the milk, slowly, and scrape up the browned bits on the bottom of the pan. We want the gravy to be lump-free, so we try our best to stir constantly.
We add salt and pepper and, after the gravy comes to a boil, we simmer gently for about 5 minutes. It is thick, free from lumps, and nicely seasoned.
We serve the gravy over biscuits with the sausage on the side.