Yes, one or two days a year we all need three ovens, and a roaster oven is quite a good way to extend your capabilities.

You absolutely can cook your casseroles in the roaster oven; indeed, we recommend it over using the roaster for the turkey. Place them on the rack and use the time and temperature you normally would. If you can restrain yourself, don’t check the progress of the casseroles until they should be nearly done, since you lose a lot of heat when you open the roaster’s lid.

Note: many roaster ovens require you to set the cooking time as well as the temperature. If you don’t set the cooking time, it is likely to shut off after about an hour as a safety measure, and you are likely to be scratching your head, wondering why the casseroles are not getting done….