For the panna cotta, pour the whipped cream into a thick-bottomed saucepan and bring to a simmer. Simmer so that the liquid is just moving, but not too violently. Simmer for three hours.
The liquid should reduce by about half and become thick and golden. Then pour into small jars, cool in the refrigerator for several hours and serve cold.
To accompany the panna cotta, which is very rich, it is best to serve fresh or marinated seasonal fruit. The indicated quantity is enough for 9 small jars.
The half-full glasses can then be topped up with lightly sugared blackberries, for example.