Just boil small cartons of buttermilk, let them cool and drain. (all-thats-jas.com)
The new package allows dairy and juice drinks to be produced and distributed in small carton pouches at room temperature, and subsequently turned into frozen products in shops or in a consumer's home (tetrapak.com)
I figured it would be easier to buy small cartons than a big pot, for most people. (all-thats-jas.com)