Using two 1-quart resealable plastic bags, place 1 bag inside the other. Place the first 5 ingredients inside the inner bag. Seal both bags, pressing out as much air as possible.

Place the 2 bags in a gallon-size resealable plastic freezer bag. Add ice and salt. Seal bag, again pressing out as much air as possible.

Shake and knead cream mixture until thickened, about 5 minutes. (If desired, wear mittens or wrap bags in a kitchen towel while shaking to protect hands from the cold ice)