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 filled with ice and salt. Shake the bag for five minutes. Kids love that part! Then, remove the smaller bag which should have turned into ice cream.