Call event dispatcher in c++

I have a user widget that i want to listen to an event and this user widget is a BP. i’ve looked at this. And i want to fire the event from an actor which doesn’t have a blueprint but only c++ code i’ve read about delegates but according to the docs. i would need this. But i can’t make a shared ref of a userwidget as it doesn’t have a default constructor and i can’t seem to grasp how to fix this.

FSharedRef< FLogWriter > LogWriter( new FLogWriter() );