The Compendium of Bheḷa 6.4.56

6.4.56

tacchṛtaṃ śītalaṃ pūtaṃkhajenābhipramanthayet | yattatra sarpirjāyetataduddhṛtya vipācayet ||

That boiled [milk], cooled and strained, one should churn with a churning stick; / whatever ghee is produced there, having extracted that, one should cook it.