To add a launcher item that runs a single specific virtual machine we can create a new launcher item as it is described here.
In short, to start a Virtual Box machine without the Virtual Box Manager we may add the following command to start the VM in the
Exec= section of a
.desktop file we can place in
Name=the name you want it to have
Exec=VirtualBox --startvm 'name of the machine'
After giving the
.desktop file executable permission we can now start our virtual machine by double-click on it, or we can drag it on the Launcher or the Desktop for convenient access.