This recipe originally appeared in "Real Simple" magazine. It is unbelievable simple, using frozen cheese ravioli, and is always a hit. Like most casseroles it is even better the second day. I use a large bag of the small cheese ravioli when I don't have the large sized ravioli and it turns out just fine. I also use a large bag of chopped spinach rather than the 10 oz box and I increase the mozzarella to 12 oz. Super simple when you're in a hurry.