This seafood casserole recipe combines flaky flounder, tender shrimp, scallops, and lump crabmeat with a rich Dijon cream sauce flavored with white wine and Old Bay. It bakes up bubbling and savory, making it a comforting seafood dinner that still feels special enough for guests.
When you want a seafood main course that brings several favorites together in one dish, this casserole is a great choice. The flounder creates a delicate base, while shrimp, scallops, and crab add different textures and plenty of seafood flavor.
The sauce is what ties everything together. Heavy cream and chicken stock give it body, Dijon adds gentle tang, and a splash of white wine brightens the richer ingredients. A butter-and-flour thickener keeps the sauce creamy enough to coat the seafood instead of becoming watery in the oven.
Because the flounder gets a short head start in the oven and the shellfish is only briefly seared, each type of seafood can finish cooking without spending too long over direct heat. The result is a warm, creamy casserole that works especially well for a cozy dinner, holiday meal, or seafood-focused weekend menu.
Seafood Casserole Recipe Ingredients
Flounder: Mild, delicate fillets form the bottom layer of the casserole and absorb some of the seasoned cream sauce as they bake.
Large shrimp: Peeled and deveined shrimp bring a firm, juicy bite and need only a quick sear before baking.
Sea scallops: Large scallops add a tender, slightly sweet seafood flavor. Searing them very briefly helps them hold their texture.
Lump crabmeat: Adds delicate crab flavor without requiring additional cooking before the casserole goes into the oven. Check it carefully for small pieces of shell.
Unsalted butter: Used both for sautéing the shellfish and for making the flour mixture that thickens the sauce.
All-purpose flour: Combines with softened butter to create a smooth thickener for the cream sauce.
Heavy cream: Gives the casserole its rich, velvety consistency.
Chicken stock: Loosens the cream and creates enough sauce to generously coat the seafood.
Dry white wine: Deglazes the skillet after the shrimp and scallops are seared, picking up their flavorful browned bits.
Dijon mustard: Adds a subtle sharpness that balances the butter and cream without overpowering the seafood.
Garlic and onion powders: Season the sauce evenly while keeping its texture smooth.
Black pepper: Adds a mild peppery finish to the creamy base.
Old Bay seasoning: Provides the familiar savory seafood seasoning on the flounder and can also be sprinkled lightly over the finished casserole.
Italian parsley: An optional fresh garnish that adds color and a clean herbal finish just before serving.
Cooking Steps
STEP 1: Heat the oven to 350°F. Arrange the flounder portions in individual oven-safe casserole dishes or a suitably sized baking dish. Add just a small splash of water around the fish and season the fillets lightly with Old Bay.
STEP 2: Bake the flounder for about 10 minutes. This partial bake gives the fish a head start before the heavier seafood topping is added. Remove the dish from the oven and carefully pour off any accumulated liquid so it does not thin the cream sauce later.
STEP 3: While the flounder is baking, melt half of the butter in a large skillet over medium-high heat. Add the shrimp and scallops once the skillet is hot. Sauté them for roughly one minute, just long enough to lightly sear their surfaces. They should not be fully cooked at this stage because they will finish in the oven.
STEP 4: Pour the white wine into the skillet and gently scrape up the flavorful bits from the bottom. Stir in the heavy cream, chicken stock, Dijon mustard, garlic powder, onion powder, and black pepper. Let the mixture cook for another minute, then transfer the shrimp and scallops to a plate while you finish the sauce.
STEP 5: Blend the remaining butter with the flour until you have a smooth paste. Whisk or stir this mixture gradually into the warm sauce. Reduce the heat to low and simmer gently until the sauce thickens enough to lightly coat a spoon. Avoid aggressively boiling the cream sauce.
STEP 6: Remove the thickened sauce from the heat. Return the shrimp and scallops to the skillet, then gently fold in the lump crabmeat. Stir only enough to distribute everything through the sauce so the crab remains in larger pieces.
STEP 7: Spoon the creamy seafood mixture over the partially baked flounder. Sprinkle the surface with a little more Old Bay if you prefer a stronger seasoned finish. Return the casserole to the oven and bake for about 25 minutes, until the sauce is bubbling and the top has taken on a light golden appearance. Let it rest briefly, then garnish with chopped Italian parsley before serving.
Recipe Tips
- Keep the first sear brief. The shrimp and scallops continue cooking in the oven, so fully cooking them in the skillet can leave them firmer than intended.
- Drain the flounder after its first bake. Removing the released liquid helps preserve the creamy consistency of the finished sauce.
- Thicken before returning the seafood. Let the butter-and-flour mixture do its job while the shellfish is out of the skillet, then fold everything back in once the sauce is ready.
Can I prepare seafood casserole ahead of time?
You can prepare portions of the casserole in advance, but seafood is at its best when it is not repeatedly heated. The cream sauce can be prepared ahead and refrigerated separately. For the most reliable texture, sear and assemble the seafood closer to baking time.
Can I make this without white wine?
Yes. Replace the small amount of white wine with additional chicken stock. You will lose a little acidity and complexity, but the Dijon mustard still provides enough tang to keep the cream sauce from tasting overly heavy.
How do I keep shrimp and scallops tender?
Avoid cooking them completely during the initial sauté. They need only a quick sear before being removed from the skillet. The seafood will continue cooking after it is covered with sauce and baked, so this short first cooking stage is important.
Can I bake everything in one casserole dish?
Yes. Individual dishes give the recipe an attractive restaurant-style presentation, but one appropriately sized baking dish works just as well. Arrange the flounder in a single layer so it cooks evenly before spreading the creamy seafood mixture over the top.
How do I know when the casserole is ready?
The sauce should be visibly bubbling around the seafood and the casserole should be thoroughly heated through. The flounder should separate easily into flakes, while the shrimp should be opaque and the scallops tender. Avoid extending the baking time unnecessarily once the seafood is cooked.
Perfect Pairings
A simple green salad makes an excellent side because its freshness balances the creamy seafood sauce. Choose a lightly dressed salad rather than one with a heavy creamy dressing.
Roasted or steamed vegetables are another good option. Asparagus, green beans, or broccoli provide a straightforward side that does not compete with the shrimp, crab, scallops, and flounder.
For a heartier meal, serve the casserole with rice, roasted potatoes, or crusty bread. Each can catch the extra Dijon cream sauce left in the dish, making the meal feel especially satisfying.
Keeping Leftovers Fresh
Allow leftover seafood casserole to cool before transferring it to a covered container. Refrigerate it promptly and use it within about 3 days for the best texture and flavor.
To reheat, place a portion in an oven-safe dish, cover loosely, and warm at about 325°F until heated through. Gentle oven reheating is preferable to high heat because shrimp, scallops, and flounder can become tough when reheated too aggressively.
You can freeze the casserole for up to about 1 month, although freezing is not ideal for this particular dish. Cream sauces may separate slightly after thawing, and previously cooked seafood can lose some of its tenderness. If you do freeze it, thaw overnight in the refrigerator and reheat slowly, stirring the sauce gently where possible to bring the consistency back together.
Seafood Casserole Recipe
Ingredients
Seafood
- 4 ounces flounder fillets separated into two portions
- 6 large shrimp peeled and deveined
- 4 ounces lump crabmeat carefully checked for shell fragments
- 6 large sea scallops
Cream Sauce
- ¾ cup chicken stock
- 2 tablespoons all-purpose flour for thickening
- ½ teaspoon onion powder
- 4 tablespoons unsalted butter divided
- 1 fluid ounce white wine
- ¼ teaspoon ground black pepper
- ½ cup heavy cream
- 1 tablespoon Dijon mustard
- ½ teaspoon garlic powder
Seasoning and Garnish
- ½ teaspoon Old Bay seasoning plus additional seasoning for the top if desired
- ½ teaspoon freshly chopped Italian parsley optional for garnish
Instructions
- Melt 2 tablespoons of the butter in a large skillet over medium-high heat. Once the pan is hot, add the peeled shrimp and scallops. Sauté for approximately 1 minute, allowing the exterior of the seafood to develop a light sear.
- Pour the white wine into the skillet to deglaze the pan. Add the heavy cream, chicken stock, Dijon mustard, garlic powder, onion powder, and black pepper. Continue cooking for approximately 1 additional minute.
- Remove the shrimp and scallops from the skillet and reserve them while preparing the sauce.
- Combine the remaining 2 tablespoons of butter with the all-purpose flour to form a beurre manié. Add this butter-and-flour mixture to the seafood sauce remaining in the skillet.
- Reduce the heat to low and allow the sauce to simmer until it reaches a suitably thick and creamy consistency.
- Remove the skillet from the heat. Return the seared shrimp and scallops to the sauce, then gently fold in the lump crabmeat until the seafood is evenly coated. Set the mixture aside.
- Preheat the oven to 350°F (175°C).
- Arrange the two portions of flounder in the bottoms of individual casserole dishes. Add a small amount of water to each dish and lightly season the fish with Old Bay.
- Bake the flounder for 10 minutes. Remove the dishes from the oven and carefully drain away any excess water.
- Spoon the prepared shrimp, scallop, crab, and cream sauce mixture evenly over the partially baked flounder.
- If desired, dust the top with a little additional Old Bay seasoning.
- Return the casserole dishes to the 350°F oven and bake for another 25 minutes, or until the casserole is thoroughly heated, bubbling, and lightly golden on top.
- Remove the seafood casserole from the oven and allow it to cool briefly before serving. Finish with freshly chopped Italian parsley, if using.