I need to reheat multiple lasagnas that are in the deep freezer, for a big party.?

There is no way I can thaw them in the refrigerator because they won't all fit. I can't thaw them in the microwave because they're in metal pans. How can I heat them from frozen: what temperature, for how long, etc.? Remember, this is a deep freezer, not a standard one, so they're really frozen solid.