In a large skillet over medium high heat, cook the bulk sausage until brown and crumbly.
When the sausage is done, add the butter if there is little to no residual butter in the pan. If there is excess oil for the sausage, you may not need to add butter. Ideally, you want about 3 tablespoons of fat, either from the sausage or from the melted butter.
Sprinkle sausage with flour, stir, and allow to cook for several minutes until the flour can absorb some of the fat and get golden brown.
Add the milk and stir. Continue stirring occasionally over medium heat until gravy thickens, 5-10 minutes.
