I recently purchased a pre made casserole and the instructions stated that it should be placed in a 440* oven for 55 minutes. This seems like a very hot cooking temperature to me - am I mistaken? Thanks.
Assuming the packaging means 440°F, no, that's not that insane. Casseroles are heavy, with a lot of liquid, so it takes a lot of heat to heat them up, especially if this is a frozen premade casserole. It is on the high side, so you might want to make sure it's not browning too much on the top (cover with foil to shield if necessary) or burning on the bottom. You can always reduce the heat partway through if you have to; it'll just take longer.