Start by thawing the mixed seafood if frozen, then pat it dry with paper towels to remove excess moisture.

In a large skillet, heat 1/4 cup of olive oil over medium heat. Add the finely chopped onion and sauté for about 5-7 minutes until it becomes translucent and fragrant.

Pour in the 1/2 cup of dry white wine and bring it to a gentle simmer. Let it cook for about 2-3 minutes.

Add the prepared seafood into the skillet, stirring gently. Cook for 5-7 minutes until the seafood is just cooked through.

Season with salt, freshly ground black pepper, and a pinch of nutmeg.

In a medium saucepan, melt 2 tablespoons of butter over low heat. Whisk in 1/4 cup of all-purpose flour to form a roux.

Gradually whisk in 2 cups of milk, cooking for 5-7 minutes, until thickened.

Remove from heat and stir in 1/4 cup of heavy cream, 1/4 cup of grated Parmesan cheese, and 1/4 cup of Gruyere cheese.

Gently fold the béchamel sauce into the seafood mixture and add 1 teaspoon of lemon zest and 1 tablespoon of chopped fresh parsley.

Preheat your oven to 375°F (190°C) and lightly grease a baking dish.

Spread the seafood mixture evenly in the baking dish and sprinkle with a mixture of 1/4 cup of breadcrumbs and extra grated cheese.

Bake for 20-25 minutes until bubbly and golden brown.