If you're into this kind of stuff, I highly recommend the somewhat amusing videos of Leslie Lamport himself, the creator and godfather of TLA+.

https://lamport.azurewebsites.net/video/videos.html

LearnTLA is also great: https://learntla.com/introduction/

This was excellent! Although it took me rather long to get all the way through. The authors blog looks to be very consistently insightful as well.