Preparing your Gourmet Seafood Cassolette is straightforward and rewarding. Follow these steps for a delicious outcome:

1. Preheat the Oven: Preheat your oven to 375°F (190°C).
2. Prepare the Seafood: In a large skillet over medium heat, melt a tablespoon of olive oil or butter. Add the minced garlic and shallot, sautéing until fragrant.
3. Cook the Seafood: Add shrimp, scallops, and fish pieces to the skillet. Cook for about 3-4 minutes until just opaque. Season with salt and pepper. Remove from heat.
4. Make the Sauce: In a separate saucepan, combine the heavy cream, seafood stock, Dijon mustard, lemon juice, and herbs. Simmer over low heat for about 5 minutes. Stir in half of the Gruyère cheese until melted. Season with salt and pepper as needed.
5. Combine Ingredients: In a baking dish, mix the cooked seafood with the creamy sauce until well combined.
6. Top with Cheese and Breadcrumbs: Sprinkle the remaining Gruyère cheese and bread crumbs evenly over the seafood mixture.
7. Bake: Place in the preheated oven and bake for 25-30 minutes, or until bubbly and golden brown.
8. Garnish and Serve: Remove from the oven; let it sit for a few minutes. Garnish with fresh parsley before serving.

By following these steps, you will create a stunning and flavorful Seafood Cassolette that will leave your guests in awe!