Pick a section (or sections) of the essay to specifically discuss with students. Ask about their choices, how they formed their arguments, the sources they used, etc. 

Students should not be expected to answer immediately -- it's good to give space to think -- but they should demonstrate a familiarity with their essay and be able to discuss their process. 

If you have concerns about the authenticity of an EE, let the EEC and DPC know as soon as possible. 

These should be positive meetings! The EE is done! This is not a time to talk about how the student disappointed us or all the ways they could have done better, but rather to look at what they've learned, the skills they've developed, and the ways their work may or may not inform their future studies. 

It is ok to discuss how the EE could be improved, but ideally we want those ideas to come from the students: it could be about what they'd do differently if they were to start over and do the EE again, or how they might approach an obstacle they faced from a different perspective. All of the essays can be better, for sure, but we want to highlight the success of having a finished product rather than the shortcomings. 

This often helps students with their final reflections, in particular. 

The biggest "lessons" could be related to the subject or topic, the nature of research or academic work, or things they learned about themselves and their abilities. From my own reflection sessions, I've had students talk about things like the importance of primary vs secondary sources for historians, or another student whose biggest takeaway was more personal: they were pleased they were able to actually finish the essay, and that doubt had been gnawing at them.