Oysters au gratin with spinach

Preparation:

Preparation: Clean and wash the spinach. Put them in a saucepan with a pinch of salt and cook over low heat for 5 minutes. Drain them, squeeze them and chop them coarsely. Heat the oil in a pan, add the spinach, pepper and cook for 3 minutes. Put the oysters and chopped shallots in a saucepan, cover and cook over high heat for 5 minutes until the shells open. Remove from the heat and shell the molluscs keeping aside the filtered cooking liquid. For the white sauce, cream the butter, add the cream and flour and dilute with the oyster cooking juices necessary to obtain a soft and creamy sauce. Add the oysters and spinach, put the mixture in a buttered baking dish; sprinkle with gruyere and grate in the oven at 220 degrees for 5/10 minutes. Serve immediately.