I've neve used them personally but I know parted can create them and it looks like the kernel option is CONFIG_EFI_PARTITION which is on by default in Debian, I don't have an Ubuntu machine to check ...

mbr2gpt /convert /disk:X /allowFullOS After conversion, go back to Step 2 and confirm the partition style is now GPT. Step 4: Enable Secure Boot in BIOS Finally, restart your PC and enter the BIOS ...

Now with a little bit of searching I've found a Windows based tool that claims it can recover a GUID partition table called Partition Guru Professional Edition (the free version does not handle > 2 TB ...