Holding the Mac and cheese casserole at the temperature of 150 F is a safe temperature but three hours is a long time and the casserole may be overcooked. If cooled right away in the refrigerator, you could store the casserole for 3 to 4 days. is it safe to reheat a cooked chicken It is entirely safe to reheat a cooked chicken if that chicken was entirely cooked and kept under adequate conditions of refrigeration or freezing. My in-laws are retired farmers and love to throw large get togethers. There are always plenty of leftovers to take home. What I discovered after all these years is that they leave the leftover turkey and ham in the stove over night and pack it and freeze it (or give you leftovers to take home) in the morning. I have taken leftovers home the next day over the years without knowing that the meat was not stored properly. Luckily no one has been sick so far. I need to 'gently' get the point across to them that this is a dangerous way to store meat. Any thoughts? This is a difficult and sensitive situation! It is hard to communicate to someone that a long-time practice may not be safe. Their response will be, of course, that no one has gotten sick, so why is it a problem. Well, they may have been lucky all these years or, more likely, they have been unaware of anyone who did become ill. Was an illness