I made lasagna in a deep dark roasting pan and froze it. Now I am going to have to reheat it. How long in the oven?

2 Answers 2


There is no way to answer this. An exact calculation is next to impossible, anyway. An educated guess would have to take into account the temperature at which the lasagna is frozen, the setting you choose for your oven, the lasagna thickness, and the temperature at which you want to eat it, and will still be way too inexact, something like "between 45 and 75 minutes".

You'll just have to check it every few minutes, or put up with overheating it and then waiting for it to cool down to edible temperatures.

  • Or reheating it to a low-ish temp (under 300F) for a really long time (covered), then uncovering and cranking the heat up at the once the middle's warmed through or putting it under a broiler.
    – Joe
    Oct 31, 2013 at 15:24

Reheating a lasagna is much like cooking it in the first place: you simply want to bring it up to serving temperature (although the second time you are not so worried about browning the top).

Because you are simply heating it through until it is hot enough to be enjoyable, assuming you have thawed it first, it is going to take about the same length of time to reheat as it did to cook the first time.

The only difference really is that you might not heat it quite hot, and you don't want to over brown the top (which can be mitigated by covering it with foil).

So I would recommend starting at about 3/4 of the original bake time, and then checking it with an instant read thermometer. Starting around 150 F it really should be hot enough to serve; making it hotter is just a matter of personal preference.

Its impossible to give an exact time, because of the many variables such as the initial temperature of the casserole, the temperature of the oven, the thickness of the dish, and so on--but you should have a good estimate from when you first baked it.

  • 1
    The 3/4 of the original bake time is a good suggestion assuming that it is starting from the same temperature as the original bake. If it was thawed in a fridge, it is starting from 4 degrees, while a just-layered lasagna made with just-cooked sauces frequently starts from way above room temperature, maybe 40 degrees celsius. And besides, I read the question as intending to thaw and reheat in the same step, like frozen pizza. In both cases, the guess is not so good; it only works when starting with a thawed and warm lasagna, or when the lasagna was originally baked from refrigerated.
    – rumtscho
    Oct 31, 2013 at 14:08
  • I think 40 is a little high, as most people are uncomfortable working with food at that temperature, but yes, I specified it was already thawed. I suspect the fridge to room temperature issue is in the noise, as the casserole doesn't need to get quite as hot for re-service. I deducted about 20 F / 10 C from the cooking recommendations I gave for lasagna in another question. But as always, a test for doneness and not a time is important.
    – SAJ14SAJ
    Oct 31, 2013 at 14:24

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