Put the cream and sugar in a small
saucepan. Heat until just boiling, then
boil vigorously for 2½ mins, while stirring
constantly. Turn off the heat, stir in the
lime juice and most of the zest and divide
between 2 small pots or glasses. Chill for
at least 2 hrs (or overnight if you’re
making ahead), until set.
To serve top each posset with a few
raspberries and the remaining zest.