Clean the mushrooms and cut them into fine slices. Grate 2 knife tips of lemon peel. Peel the shallots and chop finely. Peel the garlic clove. Chop tarragon. Rinse fish and cut into medallions. Remove heads from crab tails, cut a few times with scissors and set aside. Peel the shrimp tails. Score a little lengthwise in the middle at the thick end.
In 30 g of hot butter, saute the shallots until soft. Pour in the wine. Cook the chopped shrimp heads in this broth and then strain. Let the sauce boil.
Add the mushrooms, crème fraîche, bay leaf seasoning and garlic. Season with mace. If the sauce is not creamy, thicken with flour butter.
Whip the cream until stiff. Add tarragon, shrimp tails and monkfish medallions to the sauce and cook well. Fold in whipped cream and egg yolks and gently mix into dish. Season to taste with salt and freshly ground pepper. Arrange on hot plates.