One of my favorite pastimes as a child was lying to my babysitters about what we were allowed to do when my parents were out. We could definitely use the camcorder to film a home movie pretending we were spies. They wouldn’t mind at all if I stayed up until 10:30 PM watching the Brandy Cinderella on ABC Family. And, crucially, it was 100% permitted to put on aprons and make dessert, I swear, seriously, I pinkie promise.
Most sitters met me somewhere in the middle, which meant half the movie and no-bake treats. Peanut butter buckeyes were a favorite, as well as those oat-and-chocolate drop cookies that firm up in the freezer, when I could wait that long. Then one day, a favorite ex-pre-school teacher named Karen came over with a bag of rock salt and totally changed the game. With some basic ingredients and no fancy machinery, she taught my sister and me how to make ice cream in a bag.
The process is quite simple: Fill a small zip-top bag with cold ice cream ingredients (heavy cream, half-and-half, sugar, and whatever flavorings you’d like), then seal and place that inside of a larger, gallon-sized freezer bag filled with ice and a bit of rock salt. After shaking the bag vigorously for 10–12 minutes, you end up with scoopable, creamy, perfectly-set ice cream ready to eat from the interior bag. As a second-grader, this was the closest thing to magic I’d ever experienced, especially when Karen let us raid my mom’s sprinkle collection to adorn our final bowls; years later, as a babysitter myself, I revisited the project to the same wide-eyed appreciation (mine and the kids’).
The two-bag method works because of the combination of salt and ice. Salt causes the ice in the bag to melt at a lower temperature than usual (if you’ve sprinkled salt on an icy sidewalk, you know the drill), keeping everything much colder for longer. This way, the ingredients stay super frigid while smooshed and rattled and the ice cream is good to go straight out of the bag, with no freezer wait time at the end. The result is a little less rich than conventional ice cream (there’s no eggy custard base), but that’s a fair trade for not having to break out the ice cream machine or hand-crank churn.
