You can make this up
to 2 days ahead – just put a sheet of
cling film directly onto the surface of the
custard and chill, then gently reheat in
a pan or microwave.
Put the cream and milk into a large
pan and gently bring to just below boiling
point. Meanwhile, in a large bowl, whisk
together the yolks, cornflour, sugar,
clementine zest and juice. Gradually
pour on the hot milk mixture, whisking
the sugar mixture constantly.
Wipe out the saucepan and pour the
custard mixture back into it. Heat gently,
stirring with a wooden spoon, until the
custard is thickened, coating the spoon.
Eat hot or cold.