Former 'High School Musical' star Ashley Tisdale has been teasing a #specialproject on Twitter lately. Now we know exactly what the project is, since she just dropped a new song called 'You're Always Here' on iTunes today (Dec. 16), which she has dedicated to her beloved pop pop.

Part of the proceeds from the song, her first in a long time, will benefit St. Jude Children's Research Hospital, so it has a charity element to it, as well.

The Tiz offered an insightful look into the song in the behind-the-scenes footage. The singer and actress reveals that her grandfather passed away almost two months ago. "When I was going through the first week, stuff would come to me and I was inspired to write a song and do something for him," she said.

She continued, "One of his favorite things of mine…was whenever I would sing. I haven't done music in so long and I've been recording and don't know which song to release first. This was a perfect first song to release. Chris [French], my fiance, produced and wrote it with me. He gets me on a different level."

Clearly, Tisdale and French connect on both a personal and professional plane, with Tisadale revealing that her hubby-to-be helped her translate things and understood the importance of the subject.

Towards the end of the clip, Tisdale got emotional, revealing that her grandfather really believed in her. Grab some tissues; it's really a sweet moment.

"I want to share this with my fans. Hopefully, they will like it," she said.

The clip closes with a snippet of Pop Pop Arnold singing 'Old Man River.' It's so sweet and touching.

Tisdale shared the photo below, as well.

Watch Ashley Tisdale 'You're Always Here' BTS Footage

Listen to Ashley Tisdale 'You're Always Here'