Steamed Mussels with Lemon-Saffron Sauce

Name: Steamed Mussels with Lemon-Saffron Sauce
Yield: 4 Servings
Ingredients: 1/2 cup crème fraîche; 2 large egg yolks; 1 1/2 tablespoons butter; 2 large shallots, finely chopped; 2 tablespoons Cognac or brandy; 3 tablespoons fresh lemon juice; 1 generous pinch of saffron threads; 40 mussels, scrubbed, debearded; 1 cup dry white wine; Fresh chives