I ate at Spring Hill sometime last week — for pleasure, not for work. Not only did it remind me how much I loved Mark and Marjorie Fuller’s restaurant when I reviewed it this summer, one of the newer desserts surprised and delighted me: salted popcorn ice cream. The salted-dessert trend has been burbling along for the past five years. But I’ve never had salted popcorn ice cream before. “How do they make it?” one of my tablemates asked the waitress (even better service than when I was last there, by the way).”You take a pot of cream and you fill it with as much popcorn as you can,” she said, and mimed tamping the popcorn down with both hands. “Then you let it sit overnight, strain it, and put it in the churn.” Fuller’s ice cream turned out smooth and unctuous, with the true flavor of kettle corn: sweet and salty in equal measure, with a toasty aroma. Delicious.