The mussels are cleaned, and the open mussels are discarded (if they close when lightly tapped, they are still alive and perfectly fine).
Onions, chili, and garlic are browned in olive oil in a large pot, give it about 3-4 minutes on medium heat. Add mussels and white wine, and mix everything together.
Put a lid on the pot and turn up the heat - it should boil - and wait for 5-10 minutes.
When the mussels open, strain the broth into a smaller pot. Leave the mussels in the large pot with the lid on to keep them warm.
The broth should now be reduced until you have only 2-3 tablespoons left. Increase the heat, and let it boil vigorously until almost all the liquid has evaporated. This happens relatively quickly, between 5-15 minutes, so keep a close eye to ensure it doesn't boil dry. If that happens, it would be a real shame as everything would be ruined!
When you are left with 2-3 tablespoons of concentrated stock, add the cream, bring to a brief boil, and season with salt and pepper.
Everything is mixed together with the mussels and the finely chopped parsley.