The former Fame director, who also recently helmed an episode of Hellcats, told E! Online that she enjoyed working with the cast.
"They are so much fun - Patrick Dempsey, Ellen Pompeo, Sara Ramirez, Sarah Drew, Kevin McKidd, Chandra Wilson," she said. "I had a scene today with all of them in one scene, and it was wonderful."
Allen also suggested that the episode she is directing is important, saying: "It is a big episode. It might be the biggest episode of the season - I think it is!"
Grey's Anatomy continues on December 2 at 9/8c on ABC.