I collect regional cookbooks from all my travels, plus i have a lot of essential staple cookbooks so it is hard to decide what's most important to recommend.

Definitely though I'd say The Professional Chef is a valuable asset for your cooking. It's the culinary textbook used at the CIA and can really teach you everything you need to know and includes kitchen tested gourmet recipes in every chapter.

Essentials of Classic Italian Cooking is a staple in my home and considered a bedrock of true Italian cuisine by the food editors.