Easy Seafood Casserole Recipe

There's something truly comforting about a warm, bubbling seafood casserole fresh from the oven. The creamy, savory aroma fills the kitchen, hinting at the delicious medley of tender shrimp, flaky fish, and sweet crab hidden beneath a golden, cheesy crust.

this Recipe

I first made this dish on a chilly Sunday evening when we needed something hearty but quick. It’s become one of our go-to meals when we’re craving seafood but want to skip the fuss of fancy prep. It’s easy, incredibly satisfying, and always disappears fast at the dinner table.

Let’s dive into what makes this Easy Seafood Casserole a standout favorite.

Why You'll Love This Easy Seafood Casserole Recipe

Get ready to fall head over heels for a dinner that feels like a special occasion but fits seamlessly into your weeknight rotation.

First off, it’s shockingly simple to throw together. With just a bit of chopping and mixing, you can have this casserole in the oven in under 20 minutes. No complicated steps, no fancy tools—just easy, straightforward comfort food.

It’s perfect for families, too. Mild, creamy, and filled with familiar seafood favorites, this dish is a hit even with picky eaters. And you can customize it easily based on what your crew likes or what’s in your freezer.

Budget-conscious? You’re in luck. While seafood can be pricey, this recipe makes smart use of affordable options like frozen fish fillets and imitation crab, so you can enjoy that luxurious seafood taste without blowing your grocery budget.

The best part? It’s ideal for using up leftovers or pantry staples. Have a half bag of frozen shrimp? Toss it in. A can of cream soup lingering in the back of the pantry? Perfect. This casserole thrives on flexibility.

Let’s take a closer look at the simple ingredients that make it so crave-worthy.

Ingredients Notes

The beauty of this Easy Seafood Casserole lies in how effortlessly it comes together with just a handful of well-chosen ingredients. Each component adds texture, flavor, or richness to the final bake.

Seafood is, of course, the star. I typically use a combination of shrimp, white fish (like cod or tilapia), and imitation crab meat. The shrimp adds a tender snap, the fish brings a flaky softness, and the crab gives a sweet, briny punch. You can use fresh or frozen seafood—just be sure to thaw and pat it dry first.

Cream of mushroom soup is our secret shortcut for a luscious sauce without the need to make a roux. It brings a deep, savory flavor and smooth texture that coats the seafood beautifully. You can substitute cream of celery or cream of shrimp soup if you prefer.

Mayonnaise and sour cream work together to add creaminess and tang. The mayo adds richness, while the sour cream cuts through with a light acidity that balances the richness of the dish.

Cheese, especially a sharp cheddar, adds a gooey, golden topping that browns up beautifully in the oven. You can mix a little into the filling, too, for extra decadence.

You'll also need a shallow baking dish, around 9x13 inches, and a mixing bowl. A spatula or large spoon is perfect for spreading everything evenly into your casserole dish.

How To Make This Easy Seafood Casserole

You won’t believe how quick and effortless this recipe is from start to finish. Here’s how it all comes together.

Start by preheating your oven to 350°F and lightly greasing your baking dish. If you're using frozen seafood, make sure it's fully thawed and patted dry to avoid a watery casserole.

Chop the seafood into bite-sized pieces. This ensures even cooking and makes the casserole easy to scoop and serve. Combine your seafood in a large bowl and give it a gentle mix so everything is evenly distributed.

In a separate bowl, stir together the cream of mushroom soup, mayonnaise, sour cream, and a generous handful of shredded cheddar cheese. Season with a little salt, pepper, and your favorite seafood seasoning or Old Bay. This creamy mixture forms the luscious base of the dish.

Gently fold the seafood into the sauce, being careful not to overmix. Pour the entire mixture into your prepared baking dish, smoothing the top with a spatula. Sprinkle with additional cheese or even some crushed butter crackers if you want a crispy topping.

Bake uncovered for about 30–35 minutes, or until the casserole is bubbling around the edges and golden on top. You’ll know it’s ready when the cheese is melted and slightly crisp and the seafood is cooked through.

From prep to plate, this dish takes about 45 minutes. It’s warm, satisfying, and perfect served with a side salad, rice, or some crusty bread to soak up every bite.

Storage Options

This casserole stores beautifully, making it ideal for leftovers or meal prep. Once cooled, transfer any uneaten portions to an airtight container and store in the refrigerator for up to 3 days.

If you'd like to freeze it, let the casserole cool completely. Wrap it tightly in plastic wrap and aluminum foil, or transfer it to a freezer-safe container. It will keep well in the freezer for up to 2 months. Thaw overnight in the fridge before reheating.

To reheat, cover the casserole with foil and warm it in a 325°F oven for about 20 minutes, or until heated through. You can also microwave individual portions on medium power in 60-second intervals, stirring occasionally.

Variations and Substitutions

One of the best things about this recipe is how easy it is to tweak. Whether you're missing an ingredient or just want to mix things up, here are some delicious ideas.

Try using different seafood combinations. Scallops, lobster chunks, or even canned tuna can be used in place of or alongside the shrimp and crab. Just be sure not to overcook more delicate seafood like scallops.

Swap out the cream of mushroom soup for cream of celery or cream of shrimp for a different flavor profile. If you want to skip canned soup altogether, a homemade white sauce made with butter, flour, milk, and broth works great too.

For a lower-fat version, you can use Greek yogurt instead of sour cream and light mayo in place of full-fat. The result is still creamy and satisfying, just a bit lighter.

Add in some veggies for extra color and nutrition. Peas, diced bell peppers, or sautéed mushrooms all work beautifully and pair well with the seafood flavors.

If you're gluten-free, make sure your soup and mayo are certified GF, and skip the cracker topping or replace it with crushed gluten-free chips or breadcrumbs.

Don't be afraid to experiment and make it your own. That’s the joy of a good casserole—it welcomes creativity and always satisfies.

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