The final rendition of Come What May, particularly the moment when Christian, after a long pause, sings back - confirmation that he's regained his belief in his and Satine's love. The crescendo of "Come what may"s that follows only drives it home.
For this troper it was when Satine breaks out of song to simply say: 'I love you. Till the end...of...time' to Christian. The fact that neither of them even care about the showing and are just loving one another, not acting, right there on stage is also pretty cool.
"His palette is caked, his brushes are dry, yet the genius of Henri de Toulouse-Lautrec is as fresh and alive as the day he laid them down. Here, for a brief moment, they shall be restored to his hands, and he and his beloved city and his time shall live again."