Easy Seafood Casserole Recipe

There's something magical about pulling a bubbling seafood casserole out of the oven—the aroma of buttery breadcrumbs and tender seafood fills the kitchen, and suddenly, dinner feels like a special occasion. This Easy Seafood Casserole combines creamy, cheesy goodness with a medley of shrimp, crab, and flaky white fish for the ultimate comfort food with coastal flair.

I first whipped this up on a chilly Sunday evening when I needed something cozy but a little elevated. Now it's my go-to for family gatherings or when I want to impress with minimal effort. It’s quick, budget-friendly, and always gets rave reviews.

Even better, you can prep it in advance and just pop it in the oven when you're ready to serve. Let’s dive into why this recipe will earn a permanent spot in your dinner rotation.

Why You'll Love This Easy Seafood Casserole

Get ready to fall in love with your new favorite weeknight dinner. This Easy Seafood Casserole isn’t just flavorful and satisfying—it’s surprisingly simple to make.

First off, it’s effortlessly easy. No complicated techniques or hard-to-find ingredients here. Just a few pantry staples and a bag of frozen seafood mix are all you need.

It's also budget-friendly, especially compared to eating seafood out at a restaurant. Using a frozen seafood blend and canned crab keeps things affordable without sacrificing flavor.

Need something family-friendly? This casserole is mild, creamy, and kid-approved. You can even sneak in some peas or spinach for extra nutrition without complaints.

And let’s not forget how versatile it is. You can mix and match seafood based on what you have or your personal preferences. Plus, it pairs well with everything from rice to salad to crusty bread.

Once you see how easy it is to pull off this comforting dish, you'll want to make it again and again.

Ingredients Notes

The beauty of this Easy Seafood Casserole is that it leans on simple, accessible ingredients while still tasting indulgent and restaurant-worthy.

Start with a frozen seafood mix. Most grocery stores carry a combination of shrimp, scallops, calamari, and mussels. Let it thaw before using, and pat it dry for the best texture. You can also mix in canned crabmeat or flaked cooked white fish if you'd like more variety.

Cream of mushroom soup forms the base of the sauce. It adds richness and depth without the need to make a roux from scratch. If you’re not a fan, cream of celery or cream of shrimp soup also work well.

We can’t skip the mayonnaise and sour cream—they add creaminess and tang that balances the brininess of the seafood. It might sound unusual, but trust me: it brings the whole casserole together.

A generous sprinkle of shredded cheddar cheese adds that gooey, comforting element we all crave in a casserole. It melts beautifully and gives the dish a golden, bubbly top layer.

Finally, seasoned breadcrumbs provide the perfect crunchy topping. I like to mix them with a bit of melted butter for a toasty, flavorful finish. No fancy equipment needed—just a casserole dish and a mixing bowl!

How To Make This Easy Seafood Casserole

Making this comforting casserole couldn’t be easier. You’ll go from mixing bowl to oven in under 15 minutes.

Start by preheating your oven to 350°F (175°C). While that warms up, take your thawed seafood mix and drain it well. You want it as dry as possible so the casserole doesn’t get watery. If you're using canned crab or cooked fish, flake it gently and remove any shells.

In a large bowl, combine the cream of mushroom soup, mayonnaise, and sour cream until smooth. Then fold in the seafood, half of the cheddar cheese, and a few dashes of Old Bay seasoning, if you have it. Don’t forget a little salt and pepper to taste!

Pour the mixture into a greased 9x13-inch casserole dish, spreading it evenly. Sprinkle the remaining cheese over the top. Then, in a small bowl, mix the breadcrumbs with a tablespoon of melted butter and scatter them across the surface.

Pop it into the oven and bake for 25–30 minutes, or until the top is golden and bubbling. The edges should be slightly crispy, and the cheese fully melted.

Let it rest for 5 minutes before serving to allow the sauce to thicken slightly. You’ll get beautifully scoopable portions that hold together and deliver big on flavor.

Storage Options

This Easy Seafood Casserole stores like a dream, making it perfect for leftovers or meal prep.

If you have leftovers, transfer them to an airtight container and refrigerate for up to 3 days. The flavor actually deepens a bit overnight, making for an even tastier second helping.

To freeze, portion the casserole into freezer-safe containers. It will keep well for up to 2 months. Let it thaw overnight in the fridge before reheating.

When reheating, you can use the microwave for individual portions (about 2–3 minutes, covered), or warm the entire casserole in a 300°F oven for 20 minutes. Add a fresh layer of breadcrumbs if desired for that just-baked crunch.

Variations and Substitutions

The flexibility of this recipe is one of its best features—feel free to get creative with the ingredients.

If you’re not a fan of canned soups, try making a quick homemade white sauce using butter, flour, milk, and seafood stock. It takes a few extra minutes but gives you complete control over the flavor.

For a low-carb version, skip the breadcrumbs and swap out the soup base for a creamy cauliflower purée. You can also serve the seafood mixture over spaghetti squash or riced cauliflower instead of pasta or rice.

Want to add veggies? Stir in frozen peas, chopped spinach, or even sautéed mushrooms before baking. It’s a great way to boost nutrition without losing that rich, indulgent texture.

Switch up the cheese based on what you have. Gruyère, mozzarella, or even pepper jack work beautifully and add their own twist.

And if you're serving a crowd or making this for a potluck, double the recipe and bake it in two smaller dishes for easier serving and sharing.

This Easy Seafood Casserole is proof that you don't need hours in the kitchen or a fancy seafood market haul to serve something special. With its creamy texture, rich flavor, and crispy topping, it's comfort food with a coastal vibe—and it just might become your new weeknight favorite.

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