Brown 1 roll of sausage in a large skillet on medium to high heat. Do not drain.
Turn heat down to medium. In same skillet, add 1/4 cup flour to the sausage. You want to make sure that all the grease has been dried up by the flour. Add a little more if you feel like the pan is still greasy. You shouldn't need more than 1/2 cup.
Add in two cups of milk and stir frequently. The mixture will get thick quickly, especially in the middle. Add in a half cup of milk at a time until desired consistency. If the gravy sits on the stove for very long, it will continue to thicken. Add a little more milk to thin it out.