Cook the reserved 1/5 of sausage in skillet. Once done. Add butter if there is no grease . if it has a good grease content don't add butter. You want to see some oil in the pan!
Once butter melts add flour and stir over med heat .. Slowly add about 1 cup of water a little at t a time ..1/4 .. Allow it to bubble up and it will get a bit pasty with the first couple adds.
Add milk slowly about 1/4 at a time allow to come to boil while stirring before each addition. Add salt and pepper to taste! Ya gotta taste it don't go blind! A little at a time until ya hit that spot!
Once all liquid is added continue to stir and lower heat to med low and allow to thicken.
Serve in bowl