Easy Seafood Casserole Recipe

There’s something undeniably comforting about a bubbling seafood casserole straight from the oven. With tender shrimp, flaky fish, and a creamy, cheesy sauce, this dish delivers restaurant-quality flavor in a fraction of the time.

I first made this recipe on a rainy Sunday when I needed to use up some frozen seafood and didn’t want to spend hours in the kitchen. One bite in, and it became an instant favorite—simple enough for a weeknight, yet impressive enough for guests.

The golden, buttery topping and rich filling make this Easy Seafood Casserole a dish you’ll turn to again and again. Let’s dive in.

Why You’ll Love This Easy Seafood Casserole

This casserole checks all the boxes when it comes to flavor, ease, and flexibility.

You’ll love how fast and fuss-free this recipe is. It uses everyday pantry staples and cooks up in under 45 minutes, making it ideal for busy weeknights when you still want a touch of indulgence.

It’s also budget-friendly compared to dining out. By using frozen seafood or a seafood mix, you get all the ocean flavor without breaking the bank.

Another win? It’s family-approved. The creamy texture and mild seafood flavor appeal to adults and kids alike—even picky eaters clean their plates when this is served.

Finally, it’s incredibly adaptable. You can swap in whatever seafood you have on hand, add some vegetables, or even spice it up with Cajun seasoning.

Whether you’re serving this for a cozy night in or a casual dinner with friends, it’s a guaranteed crowd-pleaser.

Ingredients Notes

This seafood casserole recipe keeps things simple without sacrificing flavor. Each ingredient brings something special to the table.

Seafood mix is the star of the show. You can use a frozen medley of shrimp, scallops, and imitation crab, or mix and match based on what’s available. Be sure to thaw and pat dry before using to avoid excess moisture.

Cream of mushroom soup forms the base of the creamy sauce. It’s a quick shortcut that brings richness and umami to the dish. For a deeper flavor, you can substitute with cream of celery or a homemade béchamel.

Shredded cheese (like cheddar or Monterey Jack) adds gooey texture and a slightly sharp flavor. It melts beautifully into the sauce, creating that irresistible pull-apart bite.

Mayonnaise and sour cream work together to balance tanginess with creaminess. Don’t skip these—this duo gives the sauce a luscious mouthfeel and depth that plain cream wouldn’t deliver.

Crushed Ritz crackers or breadcrumbs form the golden topping. When mixed with melted butter, they crisp up perfectly in the oven for a satisfying crunch.

No special equipment is required—just a standard 9x13 casserole dish, a mixing bowl, and a spoon. Minimal cleanup, maximum comfort.

How To Make This Easy Seafood Casserole

Putting this casserole together is a breeze, and you’ll be amazed at the payoff.

Start by preheating your oven to 350°F (175°C). Lightly grease your baking dish so nothing sticks. If you're using frozen seafood, make sure it's fully thawed and patted dry with paper towels.

In a large bowl, mix together the cream of mushroom soup, mayonnaise, sour cream, shredded cheese, a sprinkle of Old Bay seasoning, and a squeeze of fresh lemon juice. This is your rich, creamy base.

Fold in your seafood mix, making sure it's evenly coated. If you're adding any extras—like peas, diced bell pepper, or chopped spinach—now’s the time to stir them in.

Transfer the mixture to your prepared casserole dish and smooth the top with a spatula. Then, in a small bowl, mix crushed crackers with melted butter and sprinkle evenly over the casserole.

Pop it in the oven and bake for 30–35 minutes, until the top is golden and the casserole is bubbling around the edges. Let it cool for about 5 minutes before serving so the sauce thickens slightly and the flavors meld.

From prep to plate, the whole process takes about 45 minutes. Expect creamy, savory bites with just the right amount of crunch—pure comfort food.

Storage Options

This casserole keeps surprisingly well, making it a great option for leftovers or meal prep.

In the fridge, store any cooled leftovers in an airtight container for up to 3 days. The flavors actually deepen over time, making it even tastier the next day.

For freezing, portion individual servings into freezer-safe containers. It can be frozen for up to 2 months. When ready to eat, thaw overnight in the fridge before reheating.

To reheat, cover with foil and warm in a 325°F oven for 15–20 minutes, or microwave in 1-minute intervals until heated through. If the topping softens, you can broil for a minute or two to crisp it back up.

Variations and Substitutions

One of the best things about this recipe is how easy it is to customize.

You can switch up the seafood based on availability or taste. Try using just shrimp, flaked salmon, or a mix that includes lobster meat for a more decadent twist.

If you’re not a fan of cream of mushroom soup, go with a homemade white sauce or use cream of celery for a lighter flavor profile.

To add some vegetable goodness, stir in chopped spinach, sautéed mushrooms, or even a handful of frozen peas for color and texture.

For a spicier kick, try Cajun seasoning, a dash of hot sauce, or even a sprinkle of crushed red pepper flakes.

Prefer a lower-carb version? Skip the cracker topping and go with crushed pork rinds or parmesan cheese instead. Still crispy, still delicious.

Don’t be afraid to play with it—this recipe welcomes your creativity.

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