How extract a snapshot from a Time Machine backup to a new external HD partion so that this partion can act as a (boot) volume?

Question

I found out how to extract a snapshot from a Time Machine backup to an external hard drive. I use:

sudo tmutil restore /Volumes/TMdrive/Backups.backupdb/machinename/2021-11-30-042315/MyHD /Volumes/Safety-HD

(where Safety-HD is the external HD and TMdrive is my Time Machine backup drive).

However after running this command (and waiting for a day or so) when I look at the resulting file system on the new external HD Safety-HD I notice the files and folders from the normal machine root (like Application, Library or System) are inside a folder MyHD:

MyHD --+
       |
       +- Applications
       |
       +- Library
       |
       +- Network
       |
       +- System
       |
       +- Users
       |
       +- ...

It is obvious that I never be able to make a bootable drive out of this! - How can I tell tmutil to restore to the root of the external drive?

Note 1: I tried the -v option like in sudo tmutil restore -v ..., but I get the same resulting folder structure (plus a very long list of info in the Terminal).

Note 2: I know I can restore to the internal harddrive via Recovery HD, but firstly this doesn't work for external drives, plus it is pretty cumbersome to reboot the whole system when I just want to create a safety bootable drive from an old TM snapshot.