Once you have your cookbook in an EPUB format, there is no means to print it, as the print facility is missing in Apple Books. Your options:
- Open the original cookbook in Pages and from the Share menu > Send a Copy > Mail > PDF. That will attach a PDF of your cook book to a new email for transmission to family members. They only need a free PDF reader application (e.g. Apple's Preview, or Adobe Acrobat Reader DC), and you don't have to worry if they can open an ePUB or Pages document.
- Select your ePUB in the Finder, and right-click on it. Choose the Compress option from the Finder secondary menu, and then drag/drop that ePUB.zip file as an email attachment. The risk is that your family members may use operating systems, viewers, and have Mail transmission size restrictions on their ability to receive and read that ePUB, which they would have to unzip beforehand.