Since quesadillas are so quick to make, they're best cooked fresh, as this helps them to be nice and crispy. If you do want to reheat a quesadilla later, you can zap it briefly in the microwave. However, this will make it a little soggy. A better option is to reheat your quesadilla in the oven, a dry frying pan on the hob, or in the air fryer. Just a few minutes at a low heat should be enough to revive it, and to crisp it up again.