Bake pastry shells according to package directions. Set aside.
Place fresh parsley sprigs, fresh thyme sprigs, and bay leaf on a 6-inch square of cheesecloth; tie with string. Set aside.
Melt 2 tablespoons butter in a large skillet over medium heat; add shrimp, scallops, and crawfish, and saute 4 minutes or until done. Stir in 1/2 cup wine and 2 tablespoons flour, and cook, stirring occasionally, 5 minutes. Remove from skillet, and set aside.
Melt 1 tablespoon butter in a Dutch oven over medium heat; add shallots and mushrooms, and saute until tender. Stir in remaining 1 cup wine and herb bag. Bring to a boil. Stir in clam juice, and cook until liquid is reduced to 1 1/2 cups (about 15 to 20 minutes). Discard herb bag.
Melt remaining 2 tablespoons butter in skillet over medium heat, and add 1/3 cup flour, stirring until smooth. Cook, stirring constantly, 1 minute. Gradually stir into mushroom mixture.
Stir together yolk and sour cream. Add to mushroom mixture; cook over low heat, stirring constantly, 5 to 6 minutes. Stir in salt and pepper. Spoon evenly into pastry shells, and top with seafood sauce. Garnish, if desired.