Reserve four artichoke hearts for garnish; cut each in two or four pieces and set aside. Buzz the rest with their liquid in the blender. Make a white roux with the butter and flour, letting them cook together, stirring, without browning. Stir in the artichoke puree, any liquid from the oysters and 1 cup milk. Simmer with the green onions, garlic, thyme and parsley, salt and pepper for about 10 minutes or until the flavors are well blended. Add the oysters and the cream and heat just until the oysters plump and curl around the edges. Serve in deep bowls immediately, the top garnished with the reserved artichokes. This was printed years ago in a column in the Times-Picayune called "Pot au Feu".