Hello,
You have already been given good recipes for the basic white sausage gravy. However, they have left out the most important part which takes it from good to fantastic, and it's very simple.
Depending on the amount of gravy you're making, add a very small amount of sugar; start with 1/4 teaspoon, taste, and take it from there. Years ago, I owned my own restaurant and everyone raved about the breakfast gravy.
Add the sugar for bacon gravy as well.
Bon appetite!