When baking frozen casseroles, it's a battle to ensure that your casserole is warmed through without becoming overcooked around the edges. The best way to avoid this is by thawing your casserole in advance. But sometimes you're in need of a last-minute meal and you don't have time to thaw. Don't fret! You can still enjoy a warm, hearty meal straight from the freezer to the oven by following a few simple steps.
If you know in advance that you're going to bake your frozen casserole, it is best to thaw it beforehand. Remove your casserole from the freezer and place it in the refrigerator 24 hours before you intend to bake it. If you forget to thaw your casserole until just a few hours before you intend to bake it, it's still best to place it in the refrigerator. The longer your casserole spends thawing in the fridge, the less time it will take to bake in the oven. Remove any plastic wrap or aluminum foil from your thawed casserole before baking it.
You can bake your pre-cooked casserole while it is still frozen, but you'll have to make a few adjustments to ensure it cooks evenly. If your casserole was frozen with a layer of plastic wrap underneath the aluminum foil, remove it. Re-cover the casserole with aluminum foil. The casserole must remained covered for almost all of the cooking time to ensure even cooking.
Bake thawed casseroles according to recipe directions, adding an extra 10 minutes or so to the total cooking time. Bake frozen casseroles at the temperature stated in the recipe, but you may need to add an extra 45 minutes or even longer to the total cooking time. For casseroles that were not thawed before baking, remove the aluminum foil during the final 15 minutes of baking to allow the top to brown. With both thawed and frozen casseroles, look for the traditional signs that your casserole is finished cooking, like liquid bubbling around the edges and a nicely browned top.
When baking frozen casseroles, the best way to ensure it is evenly cooked is with an instant-read thermometer. Add 30 minutes to the total cooking time for still-frozen casseroles, then check the temperature every 15 minutes until it reaches 160 degrees Fahrenheit. For thawed casseroles, add 10 minutes to the total cooking time and check the temperature every 10 minutes until it reaches 160 degrees Fahrenheit.