Serves 8 to 10
1 tablespoon vegetable oil
2/3 cup finely chopped white mushrooms
4 tablespoons (2 ounces, ½ stick) unsalted butter
1-1/2 teaspoons very finely chopped garlic
4 large shallots, finely chopped
½ lb cooked shrimp, finely diced
1 tablespoon all-purpose flour
½ cup brandy
½ cup heavy cream
1 teaspoon ground white pepper
6 tablespoons grated Romano cheese
4 tablespoons dry breadcrumbs
¼ cup finely chopped flat-leaf parsley
1 teaspoon Kosher or sea salt
Freshly ground black pepper
½ teaspoon Cayenne pepper
2 dozen plump, salty, oysters, freshly shucked and the flat sides of the shells reserved
About 2 lbs rock salt (optional)
Lemon wedges wrapped in muslin sleeves, for serving
In a large, heavy saucepan, warm the vegetable oil and sauté the chopped mushrooms for about 4 minutes, stirring. Remove from the pan with a slotted spoon, press with another spoon to remove excess liquid and set aside. In the same pan, melt the butter over low heat and sauté the garlic and shallots for about 3 minutes, stirring frequently, until softened.
Add the diced shrimp and stir to mix, then sprinkle evenly with the flour. Stir together, add the reserved mushrooms and increase heat to medium.
Stirring constantly, deglaze the pan with the brandy. Stir in the cream and cook for 2 to 3 minutes, until smooth. Stir in the Romano, dry breadcrumbs, parsley, salt, a touch of black pepper and the Cayenne to a soft moundable consistency. Add a small amount of milk if the mixture is too thick.
Remove the pan from the heat and transfer the mixture to a glass or ceramic bowl. Cool to room temperature, then refrigerate for about 1-1/2 hours, or until thoroughly chilled.
Preheat the oven to 400 degrees. Wash the oyster shells well and pat dry. Drain the oysters and place one in each of the 24 shells, or use two smaller oysters per shell if necessary.
Place the shells in a large, heavy roasting pan lined with a ½-inch layer of rock salt, or place six filled oyster shells in each of four pie pans lined with salt (the salt keeps the shells upright during cooking and stops the delicious juices from escaping).
Top each oyster with on generous tablespoon of the Bienville mix and bake for 15 to 18 minutes, or until nicely browned.
Garnish with a wrapped lemon wedge and serve immediately.