I'm only going to assume they are stuffed with ricotta & mozzarella cheeses from the looks of them. Some places also add spinach to their stuffed shell fillings. I have not eaten the stuffed shells at the All Stars food court but have eaten the chicken parmesan a couple of times and its very good.
**edit** oops, I'm sorry, I didnt notice the vegetarian note in your post before responding about the chicken, my apologies....