The winner is “It’s your Birthday!” by Monk Turner and Fascinoma.
The “Happy Birthday To You” melody was published in the late 1800s by two sisters who taught elementary school, and it was registered for copyright, as “Happy Birthday To You” in 1935. Time Warner acquired the copyright in 1998. The song reportedly brings in two million dollars a year from licensing for films, TV shows, advertisements and the like; it won’t enter the public domain until 2030 at the earliest.
Laughing Squid: New Copyright-Free Happy Birthday Song Selected