Final answer:
It's not clear which part of the PHP framework Dr. Kaufmann finds really cool without additional context; however, features like built-in authentication, database abstraction, and ORM are often appreciated in PHP frameworks.
Step-by-step explanation:
The question regarding PHP and the specific component considered "really cool" according to Dr. Kaufmann relates to the PHP framework. Unfortunately, without additional context, it's not possible to determine exactly which part of the PHP framework Dr. Kaufmann is referring to as this can vary based on individual perspective and the specific framework in question. However, in general, many developers may find features such as built-in authentication, database abstraction, and ORM (Object-Relational Mapping) to be among the cool aspects of a PHP framework given the convenience and efficiency they provide in web application development.