Difficulty: Easy
Scrape and rinse the Bouchot mussels under cold running water until clean, discarding any that don't close when tapped. Drain well. Finely chop the parsley (about 2 tablespoons). Peel and finely chop the onions. Trim and thinly slice the celery stalk.
In a large casserole, gently soften the onions and celery in the butter over medium heat. Stir in half the chopped parsley and the saffron powder.
Pour in the white wine, season with salt and pepper, and bring to a boil. Add the mussels, stir to coat, cover, and cook over high heat until they open, shaking the pan occasionally (discard any that remain closed).
Remove the mussels from the shells. Strain the cooking juices through a fine sieve. Return the strained juices to the casserole, add 1/4 liter of water, the fish fumet, and whipping cream. Bring to a boil, stirring, then reduce heat and simmer for 5 minutes.
Gently stir in the shelled mussels. Transfer to a soup tureen, garnish with remaining parsley, and serve hot with crusty croutons and grated Parmesan cheese.
