Easy Seafood Casserole Recipe

There’s something incredibly comforting about a bubbling seafood casserole coming out of the oven—the aroma of garlic and butter mingling with tender shrimp and flaky fish is enough to make anyone’s mouth water. With a creamy, savory sauce and golden, crispy topping, this dish hits all the right notes.

I first whipped this up on a chilly Sunday when I had a mix of frozen seafood to use up. What started as a way to clear out the freezer quickly turned into one of our most-loved meals. It’s fast, fuss-free, and feels like a coastal getaway served on a plate.

Let’s dive into what makes this casserole a weeknight (and weekend) winner.

Why You’ll Love This Easy Seafood Casserole Recipe

Get ready to fall head over heels for a seafood dish that’s elegant enough for guests but simple enough for a Tuesday night.

First off, this casserole is incredibly quick to prepare. With minimal chopping and prep time, you can have it in the oven in under 20 minutes. It’s a lifesaver on those nights when cooking feels like a chore.

It’s also super budget-friendly. By using frozen seafood and pantry staples, you can create a luxurious-tasting dish without breaking the bank. Think creamy shrimp and fish for a fraction of the cost of dining out.

Another big win? It’s family-friendly. Even picky eaters tend to come around to seafood when it’s nestled in a creamy, cheesy casserole. Plus, it’s a great way to introduce seafood in a non-intimidating way.

And let’s not forget how versatile it is. Swap in crab, scallops, or even canned tuna if that’s what you’ve got. You can also sneak in spinach, mushrooms, or peas for a veggie boost.

Now that you’re ready to make this dish, let’s talk about what you’ll need.

Ingredients Notes

The magic of this easy seafood casserole lies in its balance of creamy richness and ocean-fresh flavor. With just a few well-chosen ingredients, you get a dish that tastes like it took hours to make.

Seafood mix is the star here. I like to use a combination of frozen shrimp, white fish (like cod or haddock), and a bit of crab if I have it. Make sure to thaw and pat it dry before using to prevent excess water in the casserole. You can buy a pre-mixed frozen seafood medley or mix your own.

Cream of mushroom soup forms the base of the sauce, lending a velvety texture and savory depth. You could also use cream of celery or cream of shrimp if you prefer a more delicate seafood-forward flavor.

Mayonnaise and sour cream may sound like an unusual pair, but they work beautifully together. The mayo adds richness, while the sour cream brings a slight tang that cuts through the heaviness. Together, they create a sauce that clings to every bite of seafood.

Cheddar cheese, shredded and sprinkled over the top, adds a sharp contrast to the mild seafood. It also browns beautifully in the oven, forming that irresistible golden crust. You can use mozzarella for a milder version or even a mix of cheeses.

Crushed buttery crackers or panko breadcrumbs are the final flourish. Sprinkled over the top with a little melted butter, they provide a crispy, golden contrast to the creamy filling underneath.

You’ll also need a medium casserole dish (around 9x13 inches works well), a mixing bowl, and a spoon or spatula for assembly—no fancy tools required!

How To Make This Easy Seafood Casserole Recipe

This dish comes together in a few simple steps, making it perfect for beginner cooks or anyone short on time.

Start by preheating your oven to 375°F and greasing your casserole dish lightly with cooking spray or butter. While the oven heats, thaw your frozen seafood and pat it dry with paper towels. Excess moisture can make your casserole runny, so don’t skip this step.

In a large mixing bowl, stir together the cream of mushroom soup, mayonnaise, sour cream, and half of the shredded cheese. Add in your seafood and gently fold everything together, taking care not to break up the fish pieces too much.

Spoon the mixture into your prepared casserole dish, spreading it out evenly. Sprinkle the remaining cheese over the top, followed by a generous layer of crushed crackers or breadcrumbs. Drizzle melted butter over the topping to help it brown and crisp in the oven.

Bake uncovered for 25–30 minutes, or until the casserole is bubbling around the edges and the top is golden brown. If you like a really crisp top, pop it under the broiler for an extra 2-3 minutes at the end—but watch closely to prevent burning.

Once it’s out of the oven, let the casserole sit for 5 minutes before serving. This short resting time helps everything set up so you get those perfect, scoopable portions.

From start to finish, this recipe takes about 40 minutes, making it a doable dinner even on a weeknight. Plus, it smells absolutely incredible as it bakes—get ready for everyone to drift into the kitchen asking what’s for dinner.

Storage Options

This casserole stores beautifully, making it a great option for meal prep or leftovers. Let it cool completely before transferring to airtight containers.

In the refrigerator, it will keep for up to 3 days. Just reheat portions in the microwave or in a 350°F oven until warmed through.

You can also freeze this dish, either before or after baking. If freezing before, assemble the casserole but don’t add the cracker topping. Cover tightly with foil and freeze for up to 2 months. When ready to bake, let it thaw overnight in the fridge, add the topping, and bake as directed.

If freezing after baking, let the casserole cool completely, portion it into containers, and freeze. Reheat from frozen in the microwave or oven, though the texture may be slightly softer than when freshly made.

For best results, add a fresh sprinkle of cheese or breadcrumbs before reheating to bring back that crispy finish.

Variations and Substitutions

One of the best things about this seafood casserole is how customizable it is. You can easily tailor it to your tastes or whatever ingredients you have on hand.

Don’t eat shellfish? Swap out shrimp and crab for chunks of salmon or more white fish. The creamy sauce works just as well with heartier fish options.

Looking to lighten it up? Use Greek yogurt in place of the sour cream, and try reduced-fat mayo and cheese. It won’t be quite as rich, but you’ll still get that comforting, satisfying flavor.

If you love spice, add a dash of Old Bay seasoning or a pinch of cayenne pepper to the sauce. You could also toss in some chopped jalapeños or hot sauce for a bolder kick.

Want to make it gluten-free? Use a gluten-free cream soup and swap the cracker topping for crushed gluten-free rice crackers or seasoned GF breadcrumbs.

To make it more filling, stir in a cup of cooked rice or pasta before baking. It’ll turn your casserole into a one-dish meal that’s hearty and satisfying.

This easy seafood casserole is a recipe meant to evolve. Use what you have, trust your taste buds, and don’t be afraid to try new combinations. You might just stumble upon your own new family classic—just like I did.

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