I didnt saw progress at the kitchen with the recipe book. May I sugest to add recipies that we unlock when we cook? For example, if we discover how to make meat skewers, that recipe appears in the recipe book, and include an option to make that dish, like a shortcut, if we have those ingredients. It's better this way then trying to memorize everything...
And create the imouto's favourite dishes, where she gets bonuses after eating them, like increased love rate, or getting horny easily, or tolerate more the teasing...