Access main window label from a separate project avoiding circular references C#-WPF

I had 2 projects in one solution. Project 1 needs a class from project 2 and project 2 needs a class of project 1.

The problem is: If I add a reference of project 1 in project 2, I cannot add a reference of project 2 in project 1 .
But I needed to access main window's label from different project class. This is how I achieved it
Presentation project: Enjoy !!!