Make extra stuffing and use it for Rachael's Baked Stuffed Fish!

Ingredients

• Vegetable oil, for greasing baking sheet
• 2 pounds large button mushrooms
• 1/2 stick butter
• 1 medium onion, finely chopped
• 1 shallot, finely chopped
• 1 large clove garlic, finely chopped
• 1 rib celery, finely chopped
• 1/2 large red bell pepper, finely chopped
• 1/4 cup flat-leaf parsley leaves, chopped
• 1/4 cup white wine
• 2 slices white sandwich bread, toasted and buttered then finely chopped
• 1/4 teaspoon ground thyme
• Salt and freshly ground black pepper
• 1 1/2 cups fresh or canned lump crabmeat, cleaned of shell and cartilage
• For the bechamel:
• 3 tablespoons butter
• 3 tablespoons flour
• 1 tablespoon white wine
• 1 cup milk
• 1 tablespoon fish stock
• Salt and freshly ground black pepper
• Pinch fresh nutmeg