Nora Ephron had many passions, most publicly her writing and filmmaking. But the author, screenwriter and director, who died Tuesday at age 71, also had great enthusiasm in her largely private work in her Manhattan kitchen. And she left behind a self-published cookbook, by turns droll and earnest, memorializing the zeal. Simply titled “Nora’s Cookbook” and bound with white spiral wire, the recipe collection runs 174 pages and blends Ephron’s wry observations about throwing a great dinner party and using clarified butter with relatively simple recipes for dishes like chicken salad, monkey bread and pot roast. “I have the book and use it all the time,” said producer Scott Rudin,…