Do you remember the PowerpuffGirls' episode when a wizard came and sang this: "The happiest day of my life"?

Hello guys. I have this terrible question that's annoying my mind. Well, I listened to this song once on a PPG's episode(the new series) since I was a little girl. I never knew the name of the episode or more than few details.
All I know are the lyrics of the song and the imaginary image of the "little wizard/elf" with a green hat who had performed.

Lyrics:
"Happiest day of my life
The happiest day of it
Thank you for the gift you made
From now, I will listen to you"


Moreover, I remember that in the end, the elf was actually a bad guy who intentioned to hurt PPG.


If you have any ideas of the episode title, I'll be grateful for ever!!
I wish I could listen again to that song, and remind those sweet days of childhood...

Thanks for reading too.
xoxo, Mary