There’s something magical about the combination of fresh seafood and a rich, creamy sauce baked to golden perfection.

This baked seafood casserole is my go-to when I want to impress guests—or simply treat myself to something extra special.

With flounder, shrimp, scallops, and lump crabmeat swimming in a flavorful Dijon cream sauce, every bite feels like a little coastal getaway.

Why I Love This Recipe

It’s an elegant dish that’s surprisingly easy to prepare.

Perfectly balanced between richness and freshness.

Great for dinner parties, holidays, or any seafood lover’s night in.

Flexible—you can adjust the seafood mix to your liking.

What You’ll Need (Ingredient Highlights)

Flounder fillets – delicate and mild, the perfect base for the casserole.

Shrimp & scallops – seared briefly for sweet, juicy bites.

Lump crabmeat – adds rich, buttery seafood flavor.

Butter & flour (beurre manié) – for thickening the velvety cream sauce.

Heavy cream & chicken stock – creamy, yet light enough to let the seafood shine.

Dijon mustard & white wine – bring brightness and depth to the sauce.

Old Bay seasoning & herbs – add a touch of spice and coastal flair.

Pro Tips Before You Start

Use fresh or well-thawed seafood for the best texture and flavor.

Don’t overcook the shrimp and scallops—they’ll finish in the oven.

Beurre manié (butter dredged in flour) gives the sauce a smooth, lump-free consistency.

You can swap flounder with sole or cod if needed.

How to Make Baked Seafood Casserole

Step 1: Sauté the Shrimp and Scallops

Melt butter in a skillet over medium-high heat.

Add shrimp and scallops, searing for about 1 minute.

Deglaze with white wine, then add cream, stock, Dijon mustard, and seasonings.

Sauté for 1 more minute, then remove shrimp and scallops and set aside.

Step 2: Thicken the Sauce

Add beurre manié (butter dredged in flour) to the sauce in the skillet.

Simmer gently, stirring until thickened.

Once thick, remove from heat and stir in the seared shrimp, scallops, and lump crabmeat.

Set the finished seafood mixture aside.

Step 3: Pre-Bake the Flounder

Preheat oven to 350°F.

Place flounder fillets in a casserole dish with a splash of water.

Sprinkle with Old Bay seasoning.

Bake for 10 minutes, then drain off any excess liquid.

Step 4: Assemble and Bake

Spoon the creamy seafood mixture over the baked flounder.

Sprinkle more Old Bay seasoning on top.

Bake at 350°F for 25 minutes until bubbly and lightly golden.

Step 5: Garnish and Serve

Remove from oven and let cool for a few minutes.

Top with chopped Italian parsley for color and freshness. Serve warm and enjoy!

What to Serve It With

Buttery mashed potatoes or rice pilaf

Crisp green salad with lemon vinaigrette

Garlic bread or crusty French loaf

Variations / Substitutions

Swap flounder for cod, tilapia, or sole.

Add a sprinkle of grated parmesan for a cheesy crust.

Use fish stock instead of chicken broth for deeper seafood flavor.

Stir in spinach or peas for added color and texture.

Storage & Leftovers

Store leftovers in an airtight container in the fridge for up to 2 days.

Reheat gently in the oven or microwave to preserve texture.

Not recommended for freezing due to the cream-based sauce.

FAQs

Can I make this ahead of time?
Yes, assemble everything and refrigerate. Bake just before serving.

What if I don’t have flounder?
You can substitute with any mild white fish like cod or tilapia.

Can I use frozen seafood?
Yes, just thaw completely and pat dry before cooking.

Is this dish gluten-free?
Not as written—substitute the flour for a gluten-free alternative if needed.

Can I use half-and-half instead of cream?
It will work, but the sauce may be thinner and less rich.

What’s the purpose of the beurre manié?
It thickens the sauce smoothly without clumps—much better than just flour.

Can I use pre-cooked shrimp or crab?
Yes, just stir them in at the end with the sauce—no need to sear.

Final Thoughts

This baked seafood casserole is one of those dishes that always feels a little bit fancy, yet it’s easy enough to make on a Tuesday night.

The rich, creamy Dijon sauce ties all the seafood together beautifully, and it’s impossible not to go back for seconds.