No Friday the 13th bad luck needed here - this recipe is as easy-peasy as 1-2-3! This is a great 'use-up-what's-left-in-your-fridge' meal. You can throw anything and everything into it and it will still taste great. It's just a twist on a quesadilla, making it into a casserole and serving it up like a pie. It's also easily customizable. To add more protein for example, just crumble a veggie burger into the filling or stir in some diced tofu.