Zest your lemons with a small grating size, and juice the lemons as well. Leave to the side for now.
In a medium-large saucepan, add your cream and caster sugar. Turn on the heat to a low setting, and slowly let the sugar dissolve into the cream.
Once the sugar is all dissolved, turn the heat up to a medium heat max and stir constantly.
Wait for the mixture to start boiling, and let it boil gently for 1-1.5 minutes.
Take off the heat, and add in your lemon zest and juice. Mix in.
Pour your posset mixture into some glasses, ramekins, or bowls... whatever takes your fancy!
Add some fresh raspberries to each posset and let them sink in slightly. Sprinkle over some freeze dried raspberries and let the posset's set in the fridge for 4-5 hours.
Notes
You of course don't have to add raspberries to this mixture, but I love the flavour combination.
You can also multiply up the recipe if you need. This mixture comfortably makes 4-6 posset's, but a general rule of thumb if 150ml cream, to 50g of sugar. And then 20-25ml lemon juice and zest of a lemon per quantity as well.
These will last in the fridge for 2-3 days once set.