Melt butter in a large Dutch oven over medium-high heat. Add minced shallots, and sauté 3 minutes. Add the wine and next 5 ingredients (wine through garlic); bring to a boil. Add mussels.
Cover and cook 5 minutes or until the mussels open; discard any unopened shells. Strain the mussel mixture through a cheesecloth-lined sieve into a medium bowl, reserving cooking liquid. Reserve 12 shells with meat intact.
Remove meat from the remaining shells. Chop meat and add to pan; discard shells. Add reserved cooking liquid, clam juice, black pepper, and red pepper; bring to a boil.
Reduce heat, and simmer for 5 minutes. Stir in the milk, and cook 1 minute or until soup is thoroughly heated. Pour soup into serving bowls. Top with reserved mussels and chervil.