The Bag Method
This project calls for ice, salt, quart or pint-sized Ziploc bags, and one gallon-sized Ziploc bag. We made a few additions too. We wrapped the gallon-sized Ziploc bag in a couple of plastic grocery store bags, since it had a tendency to leak. You also want a towel to hold the very cold bag as you shake the ice cream.
We really recommend doing this outside – maybe we’re just sloppy, but somehow we ended up with shards of melting ice all over our kitchen floor! It’s an outside activity, we think.
1. Make and chill the ice cream base – Make sure your ice cream mix is well-chilled – preferably overnight.
2. Bag up ice cream mix, plus ice and salt – Put no more than 2 cups of the ice cream mix in a quart baggie and seal securely. Fill a gallon-sized bag halfway up with ice, then pour in about 1/2 cup salt. Mix it around, then put in the quart size bag. Make sure the smaller bag is covered with ice.
3. Shake, shake, shake – Seal the larger bag securely and place it in a couple layers of plastic shopping bags. Shake or rotate the bag for at least five minutes – preferably 10.
4. Open and check – Open carefully to avoid getting salt in the inner bag. The ice cream should be in a soft mass by now – if not, close up again, add some ice and shake some more.