Today's Piano Puzzler

This week's contestant is Elizabeth Bird from Bozeman, Montana.  I got the hidden song very quickly, and I suspect most people will, too, or at least eventually. I thought I might also have the composer style, but alas.  But it should be very guessable for most people I think, especially if one knows classical music very well since this music here overlaps an actual piece. And since the composer is hugely well-known.