If they are true vegetarians they don't eat eggs or anything that comes from an animal. So quiche is out of the questions as is some dairy products. If they do eat cheese buy a few frozen DiGiorno pizzeria thin spinach and mushroom or there is another one with just veggies on it. They are very good, quick and easy to heat up. We use them all the time for our unexpected guests. If they don't eat cheese then make up a batch of chili, veggie soup and freeze it in small portions and it will thaw quickly. Just remember to use veggie stock.