Sarah Paulson says Diane Keaton pulled a move fitting of "The Godfather" himself ... always taking care of the little people working in the restaurants she patronized over the years.

Paulson remembered her late friend during an appearance on "Watch What Happens Live" after Andy Cohen asked her to share her favorite memory of Diane. Gallery Launch Gallery Getty

The actress takes a minute to think in the clip -- admitting she didn't realize Andy wanted to ask her about Diane -- before revealing she went to more dinners than she could count with Keaton ... who would always ask to go into the kitchen after a meal.

Instead of asking to meet the chef who prepared her food, Paulson says she went to the back to chat with the people who bussed tables and washed ditches ... givin

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