I would just say something like, "So-and-so, in her book Cooking to Kill, gives a recipe something like this one. But I have changed things a little by...." Then just write it up in your own terms, without following the original text.
Copyright issues like this are not hard to understand when you consider that it's copyright, not patent, so what's protected is the actual literal text or graphic, not the formula. Don't copy the author's text, and you're not afoul of copyright.
Crediting the formula, the ingredients and steps (not using the same words) to the original author is just courtesy.
"Kitchen duty is awarded only to those of manifest excellence..." - The Master, Dogen