Does homemade cream of mushroom soup freeze well?

It may be perfectly okay...it may separate. The blender idea is a good one. You can also heat up some cream and add it while whisking. That may bring it back together.

This probably won't help but I usually find it helpful to freeze soups minus the cream and then add it after I've defrosted and heated up. I love Mrs Wheelbarrow's mushroom soup and in the unlikely event I make too much I freeze the mushroom/stock base and then add the cream once I defrost and cook.

I think you could totally try it in the blender. Good luck!