Apparently savory ingredients in sweet pies are a longstanding tradition in Italy, particularly in the North. I've never been a fan of cooked spinach (raw is fine, as in a salad) so when I saw a sweet spinach pie recipe in the most recent issue of La Cucina Italiana (a wonderful wonderful magazine that I highly recommend subscribing to), I initially turned up my nose. But then I realized it was a page taken right from L'Opera by my novel's main character, Bartolomeo Scappi. Which means that some point I'll have to try it out!
There are a couple of recipes for sweet spinach pie, both of which seem fairly heavy on the copyright with no real mechanism to share, so alas, I'm not going to repost the full text here.