While all of the music from every game of Touhou is pretty great, EoSD had some stand-out tracks:

Apparitions Stalk the Night: https://youtu.be/0GOA3kvP3Lg?t=270

Septette for the Dead Princess: https://youtu.be/0GOA3kvP3Lg?t=2210

And of course, the one and only U.N. Owen was Her?: https://youtu.be/0GOA3kvP3Lg?t=2757

Edit: For those curious about the gameplay, this is from Embodiment of Scarlet Devil (the 6th game): https://youtu.be/zZu2O_JQ4vs

And this is from Mountain of Faith (the 10th game), boss starts at 1:05: https://youtu.be/6S2dQ8A7fm4