Fill the gelatin with water and let it swell for about 10 minutes. After that, heat the gelatin for literally 1 minute in a microwave oven at 800 W or on a steam bath without boiling.
In a saucepan or a heavy-bottomed saucepan, combine the cream, chocolate pieces, vanilla sugar (you can add cinnamon).
Heat the contents of the pot on a steam bath or microwave to dissolve the chocolate.
Add gelatin to the chocolate-cream mixture, mix.
For a more uniform panna cotta, I also filter the mixture through a sieve.
We grease the panna cotta molds with vegetable oil and distribute the chocolate mass into the molds. We cover the top of the molds with foil and send the chocolate jelly from the cream to the refrigerator for at least 3 hours, or overnight.
Prepare the sauce before serving the panna cotta. To do this, combine the cream, chocolate, and Nutella.
Melt the mixture in a steam bath or in a microwave oven (30 seconds at 800 W).
We take out the finished chocolate panna cotta from the molds by dipping the molds in hot water until the middle so that the water does not get on the chocolate-butter jelly. We shift the panna cotta to portioned plates, pour over the prepared chocolate sauce, sprinkle with chopped nuts and grated chocolate if desired.