Since I normally make a brown gravy with my meatloaf (my wife does not like ketchup so I don't do any of the ketchup based meatloaves), I like to put a slice of meatloaf in the microwave, put a spoonful of gravy on it, heat it lightly so that it is warm and the gravy just starts to melt and then put it between bread. Just warm enough and gravy just liquidy enough to eat, but better than cold and paste-like.