Step #1 Cook sausage patties in a black cast iron skillet till done, obviously.
Step #2 Then remove the sausage & put it on some paper towels to blot up some of the grease.
Step #3 Drain grease from pan leaving only enough to coat the bottom (about 2 tbsps), stirring ALL the time, add a handful of flour (3 tbsps will do) to the grease & cook it, till it turns brown.
Step #4 Add the milk to the browned flour & stir till all the lumps are gone & it's thick.
Step #5 Add the drained Ro-Tel tomatoes & stir till it's the consistency that you like.
Step #6 (add more milk if it's too thick).
Step #7 Crumble up the sausage & add back to the gravy then spoon it over hot biscuits.