Add the flour, stir and brown for several minutes, then add in 2 cups broth and gently stir until thickened.
Add this thickened gravy mixture to the slow cooker, along with the potatoes and rest of the broth.
Cook 5-6 hours on low, or until the potatoes are soft.
minutes before serving, add 1.5 cups cheese, the sour cream, and the heavy cream to the slow cooker. Using a potato masher or immersion blender, mash the potato chunks to make a smoother consistency. (I still like to leave some chunks in there, though)
Heat through, then serve. Top with bacon bits, the remaining cheese, and chives, if desired.