It's the soaring "You Have Made Me Love You," one of the most beautiful love songs I've heard in a Broadway musical. I'm actually very surprised that I haven't yet posted this song here during one of my Valentine's Day marathons. But I did a search, and it appears as if this is the song's debut on these pages. It's sung by Leigh Beery, who got a Tony nomination as Best Supporting Actress in a Musical for her performance as Roxana. Here, she sings to Christian, believing he is her great true love, unaware that it has been Cyrano who has been behind all his glorious words.
As good as all the other songs I've been posting here, you listen to this one song alone and think, "Wait, this show flopped and only ran 49 performances????" Yes, it's that beautiful. And I try very hard not to use hyperbole when describing such things. The score is by Michael J. Lewis and novelist Anthony Burgess, who did the book and lyrics.