1/2 cup milk
1/2 teaspoon vanilla
1 1/2 tablespoons sugar (or to taste)
6 tablespoons salt
Put milk, vanilla and sugar into a pint or quart-sized freezer bag. Seal well.
Fill a large, gallon-sized freezer bag with ice. Add the salt. (We used rock salt.)
Put the smaller bag into the larger bag and seal.
Shake and mix until the ice cream thickens, about 10 minutes. You can also let the kids gently throw the bag back and forth to help mix the ice cream. The bag gets very cold, so you might want to use towels to hold it. Makes for a fun family night or Birthday activity.