Name: Seafood Gratin Recipe
Prep time: 20 min
Cook time: 25 min
Total time: 45 min
Ingredients: 8 ounces shrimp, peeled and deveined; 8 ounces scallops, patted dry; 4 ounces firm white fish fillet, cut into 1-inch pieces; 2 tablespoons unsalted butter; 1 tablespoon olive oil; 2 cloves garlic, minced; 1/2 cup dry white wine; 3/4 cup heavy cream; 1/2 cup fish or seafood stock; 1 teaspoon Dijon mustard; 1/4 teaspoon paprika; 1/4 teaspoon black pepper; 1/2 teaspoon salt, or to taste; 1/4 cup grated Parmesan cheese; 1/2 cup shredded Gruyère or Swiss cheese; 1/2 cup panko breadcrumbs; 1 tablespoon chopped fresh parsley; 1 tablespoon melted butter

Seafood Gratin Recipe tastes rich, creamy, and cheesy with tender bites of shrimp, scallops, and flaky fish tucked under a golden breadcrumb crust. It works well for cozy date nights, small dinner parties, or a “wow” family meal, and you can get it on the table in about 50–60 minutes total. I still remember burning my first gratin under the broiler, so you can learn from my mistakes instead of repeating them.

Why Seafood Gratin Recipe Is Worth It

This Seafood Gratin Recipe gives you restaurant-level flavor with simple supermarket ingredients. The sauce tastes silky and cheesy, the seafood stays juicy, and the top turns crisp and golden in the oven.

You can prep it ahead, stash it in the fridge, then bake when guests arrive. It also stretches pricier seafood with a creamy base and breadcrumbs, so you get a luxurious dish without a wild grocery bill.

“This Seafood Gratin Recipe tasted like a fancy coastal bistro dinner but came from my tiny apartment oven ★★★★★”

Ingredients You Need

Seafood

8 oz shrimp, peeled and deveined
- Medium or large work well; I like 21/25 size so they stay plump.
8 oz sea scallops, side muscle removed
- If scallops run large, cut them in half so they cook evenly.
8 oz firm white fish, cut in 1-inch chunks
- Cod, haddock, halibut, or tilapia all work; frozen fish works if you thaw and pat dry.
4 oz lump crab meat (optional but amazing)
- Canned or refrigerated both work; drain well so it does not water down the sauce.

You can mix and match based on what you find on sale. Just aim for about 1½–2 pounds total seafood.

Sauce Base

3 tbsp unsalted butter
2 tbsp olive oil
1 small shallot or ½ small onion, finely minced
2 cloves garlic, minced
3 tbsp all-purpose flour
1½ cups whole milk
- You can swap half-and-half for extra richness or 2% milk if you want it a bit lighter.
½ cup seafood stock, clam juice, or chicken broth
- Pantry shortcut: use low-sodium chicken broth if you do not keep seafood stock around.
½ cup grated Parmesan cheese
- I like to grate from a wedge; pre-grated works in a pinch but melts less smoothly.
½ cup shredded Gruyère or Swiss cheese
- You can use sharp white cheddar if that fits your budget better.
2 tsp Dijon mustard
½ tsp smoked paprika or sweet paprika
¼ tsp cayenne pepper (optional, for a little heat)
1–2 tbsp fresh lemon juice
2 tbsp chopped fresh parsley or chives
¾ tsp kosher salt, plus more to taste
½ tsp black pepper

Topping

1 cup panko breadcrumbs
- Regular breadcrumbs work, but panko gives a crunchier top.
2 tbsp melted butter
¼ cup grated Parmesan
1 tbsp chopped fresh parsley
Pinch of salt and pepper

Optional Add-Ins

½ cup frozen peas, thawed and patted dry
½ cup sautéed sliced mushrooms
½ cup blanched small broccoli florets

Equipment

10–12 inch oven-safe skillet or large sauté pan
2–2½ quart baking dish (or 4–6 individual gratin dishes / ramekins)
Medium saucepan (if you prefer to make sauce separately)
Whisk
Cutting board and sharp knife
Measuring cups and spoons
Mixing bowl for topping

Quick Tips & substitutions

Use thawed, well-dried seafood so the sauce stays thick and creamy.
If you use frozen shrimp or fish, thaw in the fridge, then pat dry with paper towels.
Swap scallops with extra shrimp if scallops cost too much or look iffy.
Use all shrimp and fish if you skip crab; just keep the total seafood around 1½–2 pounds.
Stir the sauce constantly after you add flour and milk so it stays smooth and lump-free.
Taste the sauce before you add seafood and adjust salt, pepper, and lemon.
Use sharp cheddar instead of Gruyère if that fits your budget or pantry.
Use gluten-free panko and a 1:1 gluten-free flour blend if you avoid gluten.
Bake the gratin on a sheet pan to catch any bubbly overflow and keep your oven clean.
Broil at the end only until golden; keep the door slightly open and watch like a hawk.

How to Make Seafood Gratin Recipe

Step 1: Prep and preheat

Preheat your oven to 400°F (200°C). Grease your baking dish or individual gratin dishes with butter or a light coat of oil. Pat all seafood dry with paper towels and cut any large pieces into 1-inch chunks so everything cooks at the same rate.

Season the seafood lightly with salt and pepper and set it aside. If you use peas or other veggies, thaw or cook them now and pat them dry.

Step 2: Sauté aromatics

Heat a large skillet over medium heat and add the butter and olive oil. When the butter melts and starts to foam, add the minced shallot and a pinch of salt. Cook 2–3 minutes until the shallot softens and turns translucent.

Add the garlic and cook about 30 seconds until fragrant. Do not let the garlic brown or it will taste bitter.

Step 3: Build the roux

Sprinkle the flour over the butter and shallot mixture. Stir constantly with a wooden spoon or spatula and cook 1–2 minutes until the flour smells toasty. You want a pale blond color, not dark brown.

Switch to a whisk and slowly pour in the milk while you whisk. Whisk vigorously so the mixture stays smooth and thickens evenly.

Step 4: Add stock and seasonings

Pour in the seafood stock or broth while you whisk. Bring the mixture to a gentle simmer and cook 3–5 minutes, whisking often, until it thickens to a sauce that coats the back of a spoon. If it looks too thick, splash in a bit more milk or stock.

Stir in Dijon mustard, paprika, cayenne (if you use it), salt, and pepper. Taste and adjust seasoning so the sauce tastes slightly salty and flavorful; the seafood will mellow it a bit.

Step 5: Add cheese and lemon

Turn the heat to low. Add the Parmesan and Gruyère in small handfuls while you stir. Let each handful melt before you add the next so the sauce stays smooth.

Stir in lemon juice and chopped parsley or chives. Taste again and tweak salt, pepper, or lemon until the sauce tastes bright, cheesy, and rich.

Step 6: Combine seafood and sauce

Turn off the heat. Gently fold the shrimp, scallops, fish, and crab (if you use it) into the warm sauce. Add peas or other veggies now if you want them.

Stir just enough to coat everything without breaking up the fish too much. The seafood will still look raw; the oven will cook it through.

Step 7: Transfer to baking dish

Spoon the seafood and sauce mixture into your prepared baking dish or divide it among individual dishes. Spread it into an even layer so it bakes uniformly. Tap the dish lightly on the counter to settle the sauce and remove air pockets.

If the sauce looks very thick, drizzle a tablespoon or two of milk around the edges. The sauce will thicken more in the oven, so you want it slightly looser than you think.

Step 8: Mix the topping

In a small bowl, combine panko breadcrumbs, melted butter, Parmesan, parsley, salt, and pepper. Stir until the breadcrumbs soak up the butter and look evenly moistened. You want a sandy, slightly clumpy texture.

Taste a pinch of the topping and adjust salt if needed. That tiny step makes the crust taste extra flavorful.

Step 9: Top and bake

Sprinkle the breadcrumb mixture evenly over the seafood mixture. Do not pack it down; keep it fluffy so it browns nicely. Place the dish on a rimmed baking sheet.

Bake at 400°F for 18–25 minutes, depending on the depth of your dish. The gratin should bubble around the edges, the topping should look golden, and the shrimp should turn pink and opaque.

Step 10: Optional broil and rest

If you want a deeper golden crust, switch the oven to broil on high. Broil 1–3 minutes, watching closely so the topping does not burn. Rotate the dish if one side browns faster.

Remove the gratin and let it rest 5–10 minutes. The sauce will thicken slightly and the seafood juices will settle, which gives you perfect scoops instead of soupy puddles.

Recipe Variations

Gluten-free: Use gluten-free panko and a 1:1 gluten-free flour blend in the sauce.
Lighter version: Use 2% milk, reduce cheese by one-third, and add extra veggies like broccoli or spinach.
Low carb: Skip the breadcrumbs and top with extra grated Parmesan and crushed pork rinds or almond flour.
Spicy: Add extra cayenne, a pinch of red pepper flakes, or a minced jalapeño with the shallot.
Extra veggie: Stir in blanched asparagus tips, sautéed mushrooms, or wilted spinach.
No shellfish: Use only fish and scallops or only fish and shrimp, depending on allergies and preferences.
Kid-friendly: Use mild cheddar, skip cayenne, and chop seafood smaller so picky eaters see fewer “mystery chunks.”

Ways to Serve Seafood Gratin Recipe

Spoon over fluffy white rice, brown rice, or garlic butter rice.
Serve with crusty bread or garlic toast to scoop up the creamy sauce.
Pair with a simple green salad with lemony dressing.
Add steamed green beans, roasted asparagus, or sautéed zucchini on the side.
Serve in individual ramekins with a side of mashed potatoes.
Spoon over cooked pasta or egg noodles for a seafood mac-and-cheese vibe.

Storage Success

Let the Seafood Gratin Recipe cool to room temperature, then cover tightly and store in the fridge for up to 2 days. Reheat portions in a 325°F oven until hot and bubbly, or warm gently on the stove with a splash of milk to loosen the sauce. You can freeze leftovers in airtight containers for up to 1 month, though the sauce may separate slightly. Stir gently while reheating and add a bit of cream or milk to bring it back to a smooth, creamy texture.