Hilary Duff -
What Dreams Are Made Of from The Lizzie McGuire Movie (2003) (Search it's on YouTube)
Not the unremarkable soundtrack album version of this song, which sounds different from the far better version of this song in the clip from the movie, where Lizzie starts out performing with Isabella, then Isabella leaves. They both happen to look a look a lot like Hilary Duff.
Some people call this the "Hey Now" song, you can hear why. The movie clip makes the song better, as you can see and hear Lizzie gaining confidence as she proceeds with her singing and has a good time performing with dancers in front of an appreciative and warmly welcoming crowd.