This is vegetarian, not plant-based or vegan, and a bit of an obvious choice, but Deborah Madison’s New Vegetarian Cooking For Everyone more or less taught me how to cook when I went vegetarian. It’s a huge book with a lot of variety, and the way it’s organized makes it really useful as a reference. Even my meat-eating parents have a copy and love it.
https://www.amazon.com/New-Vegetarian-Cooking-Everyone/dp/1607745534
Deborah Madison's Vegetarian Cooking for Everyone is a classic here, even if you eat meat as well and just want more vegetable ideas. I don't have the newer, revised edition but the original edition has been very well used in our kitchen. Bittman's How to Cook Everything Vegetarian is excellent too.
I know you're looking for specific recipes right now, but if y'all stay smitten I'd pick up Deborah Madison's Vegetarian Cooking for Everyone. I'm an omnivore and have never had a bad recipe out of this book. I found two of my favorites from it online:
Butternut Squash Gratin w/onions and sage - perfect for fall, I double the cheese
Mushroom enchiladas with epazote and green chile - if you're cool with mushrooms these are fantastic. Skip the creme fraiche/sour cream and crumble queso fresco over instead.
Pick up this book, it's seriously awesome and should give you a million ideas. http://www.amazon.com/The-New-Vegetarian-Cooking-Everyone/dp/1607745534