Exactly the same sauce parisienne as that for the poached fish filets in the preceding recipes is delicious with scallops gratinéed in their shells. This dish may be prepared ahead, and gratinéed just before serving. A fine, chilled white Burgundy or a very good white Graves would go well with it. Scallops are usually served as a first course, or as a light luncheon dish.
Add the scallops and mushrooms to the wine, and pour in enough water barely to cover ingredients. Bring to the simmer. Cover, and simmer slowly for 5 minutes. Remove scallops and mushrooms with a slotted spoon, and set aside in a bowl.
Rapidly boil down the cooking liquid until it has reduced to 1 cup.
Following the directions in sauce parisienne, cook the butter and flour slowly together for 2 minutes. Off heat, blend in the boiling cooking liquid, then the milk. Boil 1 minute. Blend the egg yolks and cream in a bowl, then beat the hot sauce into them by driblets. Return the sauce to the pan and boil, stirring, for 1 minute. Thin out with more cream if necessary. Season to taste with salt, pepper, and lemon juice. Strain.
Cut the scallops into crosswise pieces about ⅛ inch thick.
Blend two thirds of the sauce with the scallops and mushrooms. Butter the shells. Spoon the scallops and mushrooms into them, and cover with the rest of the sauce. Sprinkle with cheese and dot with butter. Arrange the shells on a broiling pan.
(*) Set aside or refrigerate until ready to gratiné.
Fifteen minutes before serving, set the scallops 8 to 9 inches under a moderately hot broiler to heat through gradually, and to brown the top of the sauce. Serve as soon as possible.