Best Classes for Power BI Report Development?

Hi,

Not sure if this was the correct subforum so I apologize in advance but it is related to development.

Basically i am a sql dev and have worked with many different reporting tools however I am now diving into Power Bi.

Most dashboards/simple reports are easy enough for me to just dive into, but I am looking to take more advanced dev classes (paid/unpaid, either or). Most of the classes that I've found (really just googling around) don't offer much insight into whether or not they cover development practices or get very detailed into creating dashboards, working with drilldowns, etc. 

Just wanted to put some feelers out for if you guys have any advice on good classes/training that are out there to take.

Thank you very much!