C't (my bible) recommends Drive Snapshot to create an image of your Windows on an external disk. (A free one-year license comes with #26 of C't.)
Windows 10 isn't supported though.
One click to create an image. One click to restore the image!
>die aktuelle Version funktioniert bereits mit Windows 10.
So you can actually use Drive SnapShot for Windows 10 too.
Looks like a Windows 95 app, eh, program. And "Copyright 2001-2007" does not sound or smell like active support and development...
My dear friend, let me tell assure you: if those nerds from C't pack it on their Weinachts-CD, it has been tested thoroughly. It's halt old Schule.
Old school = command line.
But anyway, for Windows users this tool might be absolutely sufficient, though many users could be over-challenged by this one-click thing ("oh dear! it deleted all my data!").