They are spectacular, they are extremely rigid & keep their crunch even after cooking. The flavor is really good as well, the pie doesn't really need anything else
I was wondering the same thing...and I'd try some basil in the mix too. that reminds me a bit of a zucchini/tomato pie I do (more of a quiche, I guess since there's eggs in the mix)
Indeed, there is a layer of mozzarella. Here's a picture from a different cook with the initial layer. Also, a link to a more explanatory post if you're interested in giving it a whirl: