This book from GCN by Nigel Mitchell (former Team Sky head chef) is a good read and has some handy recipes in it, although you can find most of it online, even in their own YouTube library.
https://shop.globalcyclingnetwork.co...d-cyclist-book
He's a big fan of rice cakes. I'm not so much (they don't store for as long as flapjack / oat bars).