Ice Cream in a Bag This is SOOO easy… and delicious! In a small Ziplock bag, put: 1/2 C. half and half (milk works too) 1 Tbps. sugar 1 tsp. vanilla Insert that bag into a larger, one gallon Ziplock fill with 1/2 bag of ice and 1/2 cup of salt, I used sea salt. Shake the bag for five minutes. (Kids love that part) Then, remove the smaller bag which should have turned into ice cream.