Saute sausage (no chunks) in oil. I prefer to remove the casings but you can leave them on if desired. Add chicken stock, milk, spinach, and butter to the sausage. Add the cooked potatoes and salt to taste, then serve. You can add crushed red pepper flakes if you like a little more spice.
Note: Depending on the chicken stock you use, a little chicken base or bouillon may be added to taste.