After a botched routine surgery on Julie Andrews' vocal cords tragically robbed her of her amazing vocal range, it seemed that Andrews would never sing again. But The Princess Diaries 2: Royal Engagement changed all that, when she was given "Your Crowning Glory", a song deliberately written as easy for Andrews to sing. Hearing her in a Disney film singing this simple, yet beautiful song and gaining the confidence to sing in public once more certainly qualifies this as a CMOH.
The scene with the girls from the orphanage in the second film definitely counts.
The ending of the second movie where "the sparrow takes off" and "the eagle flies for the last time". Not only is it awesome to see Mia finally crowned as queen, but almost everyone from throughout the movie, even those who had seemingly been against her or at least to enjoy her misfortunes are all there and happily join in on the Genovian national anthem, from Nicholas and the stoic new secret service agent, to her ex-fiance and his love interest, to the annoying Scottish gossip-rag journalist, even the scheming nobles from the first movie—and a song that was mostly Played for Laughs in the first movie becomes a sincere, heartfelt, even stirring performance.