If you are stockpiling casseroles such as lasagne, it can be hard to judge just how long it takes to defrost them before cooking.
For food safety reasons, you should always defrost frozen food in the refrigerator, unless the recipe specifies otherwise. For a dish such as lasagne, a full 24 hours defrost time is needed. Fortunately, if you take it out the night before, it should be fine to bake the following evening for dinner, just pay attention to the center to ensure it is fully cooked.
Your microwave also likely has a defrost setting that you can use. Don’t forget that the edges of the dish could start cooking while the middle is still frozen, depending on the size of the casserole, and what type of casserole it is. And as always, remove any tin foil you may have used for wrapping before you place it in the microwave.