Prepare and bake the biscuits according to the package instructions.
While the biscuits are baking, fry the sausage in a cast iron skillet, breaking apart with a wooden spoon. Remove from the skillet and set aside.
Make a roux by adding flour to the fat rendered from the sausage. If the mixture looks dry, add oil. Cook until the mixture resembles a paste and begins to darken. Slowly add in milk, stirring constantly with a whisk so the flour doesn’t clump. Season with salt and pepper, then add the sausage to the pan and stir to combine.
Ladle sausage gravy onto halved biscuits and serve.