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A bubbling hot seafood gratin, freshly baked and golden brown.

Classic Seafood Gratin

Indulge in a rich and creamy Classic Seafood Gratin, featuring a medley of tender seafood baked in a luxurious béchamel sauce and topped with a golden, bubbly Gruyère and panko crust. This elegant dish is perfect for a special occasion or a comforting weeknight meal.
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Prep Time 20 minutes
Cook Time 30 minutes
Total Time 50 minutes
Servings 4 people
Calories 450 kcal

Equipment

  • Skillet
  • Medium saucepan
  • Whisk
  • 1.5-quart gratin dish (or individual ramekins)
  • Small bowl
  • Oven

Ingredients
  

Seafood

  • 1 lb mixed seafood (shrimp, scallops, white fish like cod or haddock, cooked crab meat, or lobster)

Béchamel Sauce

  • 2 tablespoons unsalted butter
  • 2 tablespoons all-purpose flour
  • 2 cups whole milk warmed
  • 1/2 cup dry white wine (like Pinot Grigio or Sauvignon Blanc)
  • 1/4 cup finely chopped shallots (or yellow onion)
  • 1 clove garlic minced
  • 1/2 teaspoon Dijon mustard
  • 1/4 teaspoon nutmeg
  • Salt and freshly ground black pepper to taste

Topping & Garnish

  • 1/2 cup Gruyère cheese grated (or a mix of Swiss and Parmesan)
  • 1/4 cup panko breadcrumbs
  • 2 tablespoons fresh parsley chopped, for garnish
  • Lemon wedges for serving

Instructions
 

Prepare the Seafood

  • Pat raw shrimp or scallops dry and sauté briefly until opaque, then set aside. If using white fish, poach or steam until cooked and then flake it.

Make the Béchamel

  • Melt butter in a saucepan, then cook shallots until softened, adding minced garlic for another minute until fragrant.

Build the Sauce

  • Sprinkle flour over the shallot mixture to create a roux, stirring for 1-2 minutes. Gradually whisk in warm milk until smooth and thickened, then slowly whisk in the white wine.

Season the Sauce

  • Stir in Dijon mustard and nutmeg, then season generously with salt and pepper. Continue to cook until the sauce coats the back of a spoon, adjusting seasonings as needed.

Combine Ingredients

  • Gently fold the cooked seafood into the béchamel sauce, then transfer the mixture to a 1.5-quart gratin dish or individual ramekins.

Create the Topping

  • In a small bowl, combine grated Gruyère cheese and panko breadcrumbs, then sprinkle evenly over the seafood and sauce in the gratin dish.

Bake

  • Preheat oven to 375°F (190°C) and bake the gratin for 20-25 minutes until golden brown and bubbly. If needed, broil for the last few minutes, watching carefully to prevent burning.

Serve

  • Let the gratin rest for a few minutes before serving, then garnish with fresh chopped parsley and lemon wedges.

Notes

For extra flavor, you can add a pinch of cayenne pepper to the béchamel sauce. Feel free to use other cheeses like cheddar or mozzarella for the topping, but Gruyère provides the best flavor and browning. This gratin reheats well; store leftovers in the refrigerator and reheat in the oven or microwave. Always ensure seafood is cooked through before combining with the sauce.