See below

Im not sure this works without FRESH, REALLY FRESH, LIKE RIGHT FROM
THE COW FRESH milk. Let milk stand in earthenware pans for 12 to 24
hours (12 in summer, 24 in winter; these are English temp.s, BTW).
Carefully lift & place on a stove & simmer very slowly. Do not allow
to boil. Simmer until the shape of the bottom of the pan is sort of
outlined in the cream like a circle that is concentric to the rim.
Carefully move pan from heat & let cool 12 hours. There should be a
crust of cream at the top which can be skimmed off. It should have a
yellow color.