Make the milk scalding (not boiling) hot, and stir it quickly into the buttermilk, Let the mixture stand until cold and firm, then tip it gently on to a cloth laid over a sieve. Allow to drain until set and crumbly.
Turn gently out of the cloth on to a board, and pat squares with the side of a knife. Cut into square individual helpings, and lift them with a spatula into serving bowls.
Sprinkle each lightly with sifted caster sugar. Then pour over a small amount of single cream flavoured with sifted icing sugar, a