Mad Men' Oysters Rockefeller

rock salt
2 dozen large (or 3 to 4 dozen small) oysters, opened and on the half shell
4 medium shallots (about .25 cup), minced
1 small stalk celery, minced
1/4 cup fresh parsley, minced
3/4 cup butter, softened and divided
2 cups fresh spinach, coarsely chopped
1/3 cup soft bread crumbs
1 to 2 drops Worcestershire sauce
1/2 teaspoon salt
sprinkling of freshly ground black pepper
1 pinch cayenne pepper
2 tablespoons Pernod or Anisette

Preheat oven to 450.
Fill 4 pie or cake tins (or a baking dish large enough to hold oysters) with rock salt,
but no more than half full (use just enough salt to keep the oysters from rocking back and forth).
Place the tins in the oven briefly to warm.
Prepare the topping: Sauté the shallots, celery, and parsley in 4 tablespoons of butter in a heavy skillet for approximately 5 to 7 minutes.
Add spinach to the skillet and allow it to wilt for a minute.
Pour spinach mixture into a blender.
Add the remaining butter, bread crumbs, Worcestershire sauce, salt, peppers, and Pernod or Anisette.
Blend for a minute at medium speed.
Top each oyster with about 1 teaspoon to 1 tablespoon of the mixture, depending on the size of the oyster.
Remove the tins from the oven and embed the oysters firmly in the hot salt.
Return pans to the oven and bake for about 4 minutes, or until the butter is melted and the spinach is lightly browned on top.
Serve oysters right in the tin.