Melt 2 tablespoons unsalted butter in nonaluminum stockpot over medium-high heat. Add leek, celery, and shallots and saute until wilted and just beginning to color, about 5 minutes. Add peppercorns, allspice, bay leaf and thyme and saute 2 to 3 minutes to flavor vegetables. Add mussels and toss gently to blend. Pour in cider and bring to a simmer. Cover and steam 5 minutes. Remove opened mussels using slotted spoon and transfer to large bowl. Cover with damp cloth and keep warm. Continue cooking remaining mussels until opened, about 5 minutes. Transfer opened mussels to bowl; discard any unopened mussels. Reserve broth. Remove mussels from shells. Reserve 2 shells for each serving of soup; discard remaining shells.

Ladle reserved broth through strainer lined with several layers of moistened cheesecloth. Rinse and dry stockpot. Melt remaining 1/4 cup butter in stockpot over medium-high heat until foamy. Add flour and whisk 2 to 3 minutes. Blend in broth 1 cup at a time. Cook until mixture begins to thicken. Stir in cream, nutmeg, salt and pepper. Continue cooking until slightly thickened and very smooth. Reduce heat to low, add mussels and stir until just heated through. Taste and adjust seasoning. Ladle soup into heated bowls. Garnish with reserved shells. Sprinkle with chives and serve.

"Hearty Farmhouse Suppers" "Bon Appetit" February, 1983. Typos by Jeff Pruett.