1/2 lb white fish fillets (such as cod or halibut), cut into chunks
1/2 cup mussels (optional)
1 tablespoon olive oil
1 tablespoon butter
Salt and pepper to taste
For the Sauce:
1/4 cup butter
1 small onion (finely chopped)
2 cloves garlic (minced)
1/4 cup dry white wine
1/2 cup heavy cream
1/2 cup fish stock (or chicken broth)
1/4 cup Parmesan cheese (grated)
1 tablespoon fresh parsley (chopped)
1 tablespoon fresh thyme (chopped)
1 teaspoon Dijon mustard (optional)
Salt and pepper to taste
For the Topping:
1/2 cup panko breadcrumbs
1/4 cup grated Parmesan cheese
1 tablespoon melted butter
1 tablespoon fresh parsley (chopped)
Instructions:
Prepare the Seafood:
In a large skillet, heat olive oil and butter over medium heat. Season the shrimp, scallops, and white fish with salt and pepper.
Cook the shrimp and scallops for about 2-3 minutes until lightly golden. Remove them from the skillet and set them aside.
In the same skillet, cook the fish chunks for about 4-5 minutes, then add the mussels (if using) and cook for another 2-3 minutes. Remove from heat and set aside.
Make the Sauce:
In the same skillet, melt butter over medium heat. Add the onion and cook until softened, about 3-4 minutes.
Add garlic and cook for another minute.
Pour in the white wine and cook for 2-3 minutes, allowing the wine to reduce slightly.
Stir in the heavy cream, fish stock, Parmesan cheese, parsley, thyme, and Dijon mustard (if using). Simmer the sauce for 5-6 minutes until it thickens. Season with salt and pepper to taste.
Assemble the Cassolette:
Preheat the oven to 375°F (190°C).
In individual cassolette dishes (or one large baking dish), layer the seafood mixture, then pour the sauce evenly over the top.
In a small bowl, mix the panko breadcrumbs, Parmesan cheese, melted butter, and parsley. Sprinkle this mixture over the top of the seafood.
Bake:
Place the casseroles in the oven and bake for 12-15 minutes, or until the top is golden brown and the sauce is bubbling.
Serve:
Garnish with fresh parsley and serve immediately, ideally with crusty bread or a side of steamed vegetables.