Rotate actor via umg.widget


My question is really simple. I have a custom blueprint containing a few things (meshes, skylight, sun, etc…).

I want to be able via a slider in my widget, to rotate the actor. I can create a reference by dragging the actor in my level blueprint, but not in my widget blueprint. How do I access it to then rotate it?

I usually cast to my game instance blueprint then grab a reference to the actor. I use it as a go-between.