Seafood Gratin Recipe tastes rich, creamy, and a little bit fancy while still feeling like cozy comfort food, and it works perfectly for date night or a family Sunday dinner in under an hour. This recipe suits seafood lovers who want restaurant-style flavor with simple, grocery-store ingredients and minimal fuss. I first made a version of this on a tiny apartment stove in Boston, and my neighbors still talk about that buttery breadcrumb topping.
Why Seafood Gratin Recipe Is Worth It
This seafood gratin recipe layers tender shrimp, scallops, and flaky fish in a velvety, garlicky cream sauce with a golden, crunchy topping. The contrast of creamy filling and crisp crumbs hits every comfort-food button without feeling heavy or greasy.
You prep everything in one pan, finish it in the oven, and serve it straight from the baking dish. Cleanup stays easy, the ingredients stay flexible, and the whole thing looks like you spent way more time on it than you actually did.
“Ultra-creamy, loaded with seafood, and that cheesy crumb topping steals the show every single time. ★★★★★”
Ingredients You Need
Seafood
- 1 pound shrimp, peeled and deveined (medium or large; frozen works if you thaw and pat dry)
- 1/2 pound sea scallops or bay scallops (pat dry; if large, cut in half)
- 1/2 pound firm white fish, cut in bite-size chunks (cod, haddock, halibut, or tilapia)
- 1/2 teaspoon kosher salt
- 1/4 teaspoon black pepper
- Juice of 1/2 lemon
Sauce base
- 3 tablespoons unsalted butter
- 1 tablespoon olive oil
- 1 small yellow onion, finely chopped
- 2 cloves garlic, minced
- 2 tablespoons all-purpose flour
- 1 cup seafood stock or low-sodium chicken broth (boxed stock works great)
- 3/4 cup whole milk
- 1/2 cup heavy cream (or use all milk for a lighter sauce)
- 1 teaspoon Dijon mustard
- 1/4 teaspoon smoked paprika or sweet paprika
- 1/4 teaspoon crushed red pepper flakes (optional, for a little heat)
- 1/4 cup grated Parmesan cheese
- 1/4 cup shredded Gruyère or Swiss cheese (good-quality store brand works fine)
- Extra salt and pepper to taste
Veggies and flavor boosters
- 1 small leek, white and light green parts thinly sliced (or use 1 extra onion if you skip leeks)
- 1 small carrot, finely diced (optional, adds sweetness and color)
- 1 tablespoon chopped fresh parsley
- 1 teaspoon fresh thyme leaves or 1/2 teaspoon dried thyme
- Zest of 1/2 lemon
Topping
- 3/4 cup panko breadcrumbs (or regular dry breadcrumbs)
- 2 tablespoons melted butter
- 1/4 cup grated Parmesan cheese
- 1 tablespoon chopped fresh parsley
- Pinch of salt and pepper
Pantry shortcuts and substitutions
- Use frozen seafood mix if you want a shortcut; thaw it in the fridge and pat it very dry.
- Swap seafood stock with bottled clam juice plus water if that fits your pantry.
- Use pre-shredded cheese in a pinch, but grate a block if you want smoother melting.
- Use half-and-half instead of milk and cream if that already sits in your fridge.
Equipment list
- 10 to 12 inch oven-safe skillet or medium Dutch oven
- Cutting board and sharp knife
- Medium mixing bowl
- Whisk and wooden spoon or spatula
- Measuring cups and spoons
- Zester or small grater
- Oven-safe baking dish if you prefer to bake it separate from the skillet
Quick Tips & substitutions
- Pat all seafood very dry so the sauce stays thick and the gratin does not turn watery.
- Cut fish and scallops into similar sizes so everything cooks at the same rate.
- Use all shrimp if that fits your budget; just keep the total seafood at about 2 pounds.
- Swap milk with unsweetened oat milk and use vegan butter plus plant cream for a dairy-light version.
- Toast panko in a dry skillet for 2 to 3 minutes for extra crunch and flavor.
- Season lightly at first, then taste the sauce after adding cheese and adjust salt at the end.
- Keep the sauce slightly thicker than you think you need; seafood releases juices while it bakes.
- Add a handful of frozen peas or corn straight from the freezer for extra color and sweetness.
How to Make Seafood Gratin
1: Prep and season the seafood
Pat shrimp, scallops, and fish very dry with paper towels and place them in a large bowl. Sprinkle with salt, pepper, and lemon juice, then toss gently to coat. Set the bowl in the fridge while you start the sauce so the seafood stays cold and firm.
2: Sauté veggies and aromatics
Heat butter and olive oil in a large oven-safe skillet over medium heat. Add onion, leek, and carrot, then cook until they turn soft and lightly golden, about 7 to 8 minutes. Stir in garlic, thyme, paprika, and red pepper flakes, and cook 1 to 2 minutes until the mixture smells fragrant.
3: Build the creamy sauce
Sprinkle flour over the veggies and stir until the flour coats everything and looks slightly pasty, about 1 minute. Slowly pour in seafood stock while you whisk, and scrape the bottom of the pan to pick up browned bits. Add milk and cream, then whisk until the sauce looks smooth and starts to bubble and thicken, about 3 to 5 minutes.
4: Add cheese and bright flavors
Turn the heat to low. Stir in Dijon mustard, Parmesan, Gruyère, lemon zest, and parsley until the cheese melts and the sauce turns silky. Taste and season with more salt and pepper if needed; the sauce should taste slightly salty and very flavorful since it will coat all the seafood.
5: Combine seafood with the sauce
Remove the skillet from the heat. Gently fold the chilled seafood into the hot sauce, coating every piece without breaking up the fish. Spread the mixture into an even layer in the skillet or transfer it to a greased baking dish if you prefer a separate serving piece.
6: Mix the crunchy topping
In a small bowl, combine panko, melted butter, Parmesan, parsley, salt, and pepper. Stir until the crumbs look evenly moistened and clump slightly. Sprinkle the mixture evenly over the top of the seafood and sauce, covering the surface from edge to edge.
7: Bake to golden perfection
Heat the oven to 400°F while you prep the topping. Place the skillet or baking dish on the middle rack and bake 15 to 20 minutes, until the sauce bubbles around the edges and the topping turns golden brown. If you want deeper color, switch the oven to broil for 1 to 2 minutes and watch closely so the crumbs do not burn.
8: Rest
Remove the seafood gratin from the oven and let it rest 5 to 10 minutes so the sauce thickens slightly. Sprinkle with extra parsley and a little more lemon zest if you like a bright finish. Serve big spoonfuls while hot and enjoy that mix of creamy sauce and crunchy topping.
Recipe Variations
- Gluten-free: Use a gluten-free all-purpose flour blend and gluten-free panko or crushed gluten-free crackers.
- Lower carb: Skip the flour and thicken the sauce with a small amount of cream cheese or a cornstarch slurry.
- Extra veggie: Add sautéed mushrooms, spinach, or finely chopped fennel bulb with the onions.
- Spicy: Add extra red pepper flakes or a spoon of chili paste to the sauce.
- Extra cheesy: Top with a mix of panko and shredded Gruyère for a thicker, cheesier crust.
- Budget-friendly: Use only white fish and shrimp, or use canned crab meat instead of scallops.
Ways to Serve Seafood Gratin
- Spoon over fluffy white rice or brown rice for a cozy bowl.
- Serve with crusty bread or garlic bread to scoop up every bit of sauce.
- Pair with a simple green salad with lemony dressing for freshness.
- Serve alongside roasted asparagus, green beans, or broccoli.
- Spoon smaller portions into individual ramekins for a dinner party starter.
Storage Success
Let leftovers cool to room temperature, then cover the dish tightly or transfer portions to airtight containers. Store seafood gratin in the fridge for up to 2 days for best flavor and texture. Reheat gently in a 325°F oven until hot in the center so the sauce stays creamy and the topping regains some crunch. If the sauce thickens too much, stir in a splash of milk after reheating to loosen it slightly.
Seafood Gratin Recipe
Ingredients
Instructions
- Preheat the oven to 400°F (200°C). Lightly grease a medium baking dish.
- Pat the shrimp, scallops, and fish dry with paper towels. Toss them together with the lemon juice and set aside.
- In a medium saucepan, melt the butter over medium heat. Add the chopped onion and cook until softened, about 3–4 minutes. Stir in the garlic and cook for 30 seconds more.
- Sprinkle the flour over the onion mixture and cook, stirring, for 1–2 minutes to form a roux.
- Gradually whisk in the milk, heavy cream, and white wine (if using), stirring constantly until smooth. Cook for 3–5 minutes, until the sauce thickens enough to coat the back of a spoon.
- Season the sauce with salt, black pepper, paprika, and dried thyme. Stir in half of the Gruyère and half of the Parmesan until melted and smooth. Remove from heat.
- Spread the mixed seafood evenly in the prepared baking dish, then pour the cheese sauce over the top, making sure the seafood is mostly covered.
- In a small bowl, combine the breadcrumbs, remaining Gruyère, remaining Parmesan, chopped parsley, and olive oil. Mix until the crumbs are evenly moistened.
- Sprinkle the breadcrumb mixture evenly over the seafood and sauce.
- Bake for 18–22 minutes, or until the top is golden brown and the sauce is bubbly and the seafood is just cooked through.
- Let the gratin rest for 5 minutes before serving. Serve hot with crusty bread, rice, or a simple green salad.
Notes
Approximate per serving (4 servings): 520 calories; fat 32 g; saturated fat 17 g; carbohydrates 20 g; fiber 1 g; sugars 6 g; protein 34 g; sodium 780 mg. Values will vary based on specific seafood selection, brands, and portion size.