Gratin oysters

Preparation:

Preparation: Open the oysters, put the shells aside and filter the water. Measure the filtered water and add the wine to obtain a quantity of liquid of about 30 cl. Heat the oven to 230 degrees. Place the oysters in a saucepan, cover them with the water-wine mixture and simmer them on the heat for a couple of minutes. Drain them with a slotted spatula and place them on the shells set aside, duly washed and cleaned. Reduce the cooking liquid from the oysters by about 1/3. Work the butter with the flour to obtain a handled butter, add it a little at a time to the liquid, stirring vigorously without stopping over a moderate heat until the sauce is thick and homogeneous. Remove from the heat and, stirring constantly, add the egg yolk. Salt and add a pinch of cayenne pepper. Cover the oysters with a spoonful of sauce each, arrange them on a baking tray and leave them au gratin for ten minutes. Before serving, garnish with chopped parsley.