Although you want to eat the lasagna as soon as it comes out of the oven, it is best to be patient. Let the lasagna rest without a cover for about 15 to 20 minutes. Let it set. Resting the lasagna prevents it from being soggy. That is why some people prefer reheated lasagna more than the newly cooked one. The reheated lasagna has the chance to set, and the layers are separate and delicious. It prevents the lasagna from becoming some thick porridge.