During rehearsal Bette said, “I don’t understand how to play this. What can we do so that it’s not just a talky scene?” Mankiewicz puffed his pipe. Then he looked around the set. At last he said, “Do you see that candy jar on the piano?” He took Bette’s arm and they walked over it. The candy jar was empty. Mankiewicz called over the second prop master and said something to him. Later, when it was time to play the scene, Bette recalled what Mankiewicz had told her: “The madder you get, the more you want a piece of candy.”
(…) The cameras rolled. At Margo’s sarcastic line about Eve — “She’s a girl of so many interests” — Bette jerked open the candy jar, picked up a piece of chocolate, brought it to her mouth and amost popped it in, then threw it back in the jar. Just then Bette made a peculiar face. Mankiewicz halted the shooting. “What’s wrong?” he asked. “I’m sorry, Joe” Bette said meekly. “I didn’t mean to, but I loathe eating chocolates in the morning. Mankiewicz and Bette huddled for a conference. An other prop man was dispatched to the commissary, and when he came back he brought tiny squares of gingerbread to masquerade as chocolates.
Then the scene continued. Margo’s anger builds; so does Bill’s.
[at last] Margo opens the candy jar, grabs the seductive piece of “chocolate”, throws it in her mouth, and chews furiously, eyes bulging as she swallows, seething all the while.
And that’s how a scene that was already good on the page turned out brilliant thanks to the director’s flourishes, and thanks also to an actress who knew what to do with “a genius piece of business”, In Bette’s words.
All About “All About Eve”