I don't know if this is the song Pelagie is referring to, but here's one Wombat Stew":https://www.youtube.com/watch?v=ZFb6gP7mZZo
WOMBAT STEW
Wombat stew,
Wombat stew,
Gooey, brewy,
Yummy, chewy,
Wombat Stew.
from the children's book, by Marcia K. Vaughan (Author), Pamela Lofts (Illustrator) (1986)
Another performance, another tune:https://www.youtube.com/watch?v=XVkySEl-ExM