Discard any mussels that have opened. Scrape off barnacles and scrub mussels with a stiff brush under running water; drain.
In a 4 to 5-quart kettle over medium heat, melt the butter. Add the paprika and shallots and cook, stirring, until soft but not brown. Add the mussels in shells, parsley, peppercorns, and wine. Bring to a boil, cover, reduce heat, and simmer until the mussels open (about 6 to 8 minutes). Discard any mussels that remain closed.
Remove the mussels from the liquid. Strain the liquid through a dampened cloth and measure it. Add fish broth to make 4 cups. Return liquid to the kettle (rinsed to remove any sand).
Remove the mussels from the shells, discarding the shells. Pinch out and discard any "beards" from the mussels.
To the liquid, add the cream. Bring to a boil over high heat, reduce the heat slightly, and boil until the soup is reduced by about one-fourth. Lower heat to medium. Taste and add salt, if needed. Add the mussels and cook until just heated through. Serve hot or chilled, garnished with parsley.
Recipe courtesy Brother Rick Curry, S.J, The Secrets of Jesuit Soupmaking, 2002