There are a lot of more complicated meals, but a  really easy one that you can make ahead of time is a tinfoil meal where are you take a loaf of French bread or you can use other types and slice it an odd number of times about three-quarters of the way through.   Then you mix up a tablespoon  of au jus half a stick of butter, some garlic powder and Worcester shire sauce.  spread this in the bread like you're making french bread then layer in provolone cheese and roast beef. double wrap it in tin foil and you just have to cook it until it's warm when you're ready for it.  it is easy to prep ahead of time easy to cook and clean up after and then you have these little pull apart individual sandwiches which is why you cut it in an odd number of slices.  make some blackberry or apple crisp to go with it and some vegetables that you spice all which can be cooked in their little foil packets and you're done.