Savory Pies published by Booksumo press is free. Yeah, I know I hadn't heard of them either. I would also argue that a soufflé is not a pie. However, I made the Milky Asparagus Souffle and it was really good. Like, really good and rather easy to make. ( I mean Michael, my roommate who is a bit picky in a good way about his food - very cultivated taste buds - loved it and put it on the make again list). So if you are looking for cookbooks, it's worth a look.