It is produced by allowing unpasteurized milk to turn sour (ferment) at a specific humidity and temperature.

In Joy of Cooking, "Clabber... is milk that has soured to the stage of a firm curd but not to a separation of the whey.

[3] Clabber is sometimes a middle step in cheesemaking, such as for Uzbekistan's kurt,[4] Polish twaróg [pl] and for some cultured cheeses.

In rural areas of the Southern United States, it was commonly eaten for breakfast with brown sugar, nutmeg, cinnamon, or molasses added.

Similar foods are the South African amasi, German Dickmilch (thick milk), Scandinavian filmjölk, Russian prostokvasha, Lithuanian rūgpienis, Latvian rūgušpiens, Polish zsiadłe mleko [pl] and Hungarian aludttej.