Heat white sauce and add wine. Flour flounder and shake off excess flour. Heat butter in large pan, add floured fish, then add crayfish, tomatoes and oysters. Toss gently in the butter, move foods to one side of pan, pour over warmed brandy and light. Stir seafood into flames. Pour over 1 1/2 cups of sauce to douse flames. Add shrimp. In separate pan add some clarified butter and toss mushrooms with lemon juice and a pinch of cayenne. Add the seafood. Lay pancakes on warmed serving dish, place a large tablespoonful of mixture into the center. Fold over either side and turn whole filled pancake upside down. Continue in this manner until all pancakes are filled. Add 1 tablespoon of the cheese to the remaining sauce, spoon sauce over pancakes, dust surface with remaining cheese and place under grill to brown. Serve dusted with cayenne pepper and finely chopped parsley. Serve accompanied by lemon wedges.