We created this four panel Z Fold card at a recent class as well. I had not seen this card done before and stumbled across some instructions for it. Super quick and easy! I wish I knew where I found it - I just had my notes to recreate it from. Below is a video on how to make this card.
Here is the card completely opened up. It is a great card to embellish!
UPDATED VIDEO: This video has been updated to provide better viewing and also to provide measurements.