For a single flavoured posset

1. Blend together the berries and fizz (leave a couple out for decoration at the end). Whizz together until the puree is as smooth as you can get it, then push through a sieve using a spoon. Throw away the seeds left behind.
2. Heat the cream and sugar together on the hob, warming gently until the sugar melts.
3. Increase the heat until just boiling, then boil vigorously for 2 ½ minutes.
4. Turn off the heat and stir in the fruit puree.
5. Cool for 15 minutes before dividing between 4 small pots or glasses
6. Chill for at least 2 hours (or overnight if possible), then decorate with the berries you put to one side at the start.
7. Serve with shortbread biscuits

For the triple layered posset

1. Separate out your 3 types of berries. Blend together 140g of each type of berry with 2 tbsp of fizz. Whizz together until the puree is as smooth as you can get it, then push through a sieve using a spoon. Throw away the seeds left behind.
2. Heat 150ml cream and 3tbsp sugar together on the hob, warming gently until the sugar melts.
3. Increase the heat until just boiling, then boil vigorously for 2 ½ minutes.
4. Turn off the heat and stir in the first type of fruit puree.
5. Cool for 15 minutes before dividing between 4 small pots or glasses
6. Chill for at least 2 hours. When the first layer has set, repeat the process with your second flavour of berry, then leave that to chill. Once the second layer has set, repeat the process again with your final layer.
7. Decorate with the leftover berries and serve with shortbread biscuits