Mussel Soup with Saffron

Name: Mussel Soup with Saffron
Ingredients: 3 lb. mussels; 1 bottle dry white wine, such as a Pinot Blanc or Chardonnay; 2 tbsp. chopped shallots; 1 tbsp. minced garlic; 2 tbsp. unsalted butter; 1 medium onion; 1 large carrot; 1 tbsp. all-purpose flour; ½ tsp. saffron threads; 4 c. chicken stock or canned low-sodium chicken broth; 4 c. heavy (or whipping) cream; Coarse (kosher) salt, to taste (optional); Pinch of cayenne pepper, or to taste; Fresh lemon juice, to taste; 1 bunch chives, for garnish