What Amy Winehouse recording has just her and a bass guitar?

Hi,
I'm not real familiar with all of Amy Winehouse's discography, but I remember hearing a song by her that was just her singing along with a bass as the music... no horns/guitars/drums.
It was a really great song, but I never found out the name, and I have been unable to find it since.

Do any of you know what song I am thinking of, and do you know where I might be able to find it?

Thank you.