Flour, rather than cream, is the thickening agent in this casserole. The oysters will exude a great deal of liquid as they cook, so adjust the amount of flour according to how thick a sauce you’d like. (Three tablespoons will create a thicker sauce.) Serve it with rice and a green salad or steamed broccoli.
You'll have leftover topping, which you can use to top other casserole dishes. If the mixture hardens in the refrigerator, reheat it in the microwave for 5 to 10 seconds before using.
Make Ahead: The topping can be made up to 2 weeks in advance and refrigerated in an airtight container.
- For the topping
- 2 ounces oyster crackers or saltines
- 4 tablespoons (1/2 stick) melted unsalted butter
- 1 tablespoon finely chopped onion
- 1 tablespoon minced parsley
- 1/4 teaspoon minced thyme leaves
- For the casserole
- 3 to 4 tablespoons unsalted butter
- 2 to 3 teaspoons minced shallot
- 4 ounces sliced mushrooms
- 2 to 3 tablespoons unbleached all-purpose flour (see headnote)
- 1 tablespoon dry sherry
- 2 tablespoons dry white wine
- 1 pint shucked oysters and their juices
- Cayenne pepper
- Freshly ground black pepper
For the topping: Grind the crackers in a food processor or blender until they are evenly ground but retain some texture. Transfer the crumbs to a mixing bowl.
Melt the butter in a small saucepan, add the onion and cook until the onion has softened, about 5 minutes. Add to the crumbs along with the parsley and thyme, and mix to combine. The yield is about 1 cup. Use immediately, or cover and refrigerate.
For the casserole: Preheat the oven to 400 degrees.
Melt the butter (to taste) in a medium nonreactive saucepan over medium-high heat. Add the shallot to taste and cook for 1 minute. Stir in the mushrooms and cook for 2 minutes, stirring constantly. Remove the saucepan from the heat and stir in the flour (as needed); return it to the heat and cook, stirring constantly, for 2 or 3 minutes to cook the flour. Stir in the sherry and wine. The mixture will be thick. Add the oysters and their juices and stir to break up any lumps of flour. Season with a generous pinch of cayenne pepper and with salt and pepper to taste. Transfer the mixture to a shallow baking dish and sprinkle with 1/3 to 1/2 cup of the cracker crumb mixture, or more to taste. Bake for 10 to 15 minutes or until the oysters are cooked and the top is browned. Serve right away.
Adapted from a recipe from Legal Seafood.
Tested by Jane Touzalin.
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