Easy Seafood Casserole Recipe

There’s something undeniably comforting about a creamy, bubbling casserole straight from the oven—and this Easy Seafood Casserole takes that comfort to new depths of flavor. With tender shrimp, flaky white fish, and a buttery cracker topping, it’s the kind of dish that feels both fancy and familiar.

I discovered this gem while searching for a way to stretch a bag of frozen seafood into a full meal. It’s since become a go-to in our home, ideal for weeknights when we’re craving something indulgent yet incredibly easy to pull together.

Whether you're hosting guests or just want to treat yourself to something special midweek, this seafood casserole delivers big-time taste with minimal effort. Let’s dive into why this recipe deserves a spot in your regular rotation.

Why You’ll Love This Easy Seafood Casserole

This recipe isn’t just delicious—it checks off all the boxes for a weeknight dinner or even a potluck winner. Here’s what makes it so irresistible:

First off, it’s truly easy to make. With just a few steps and one baking dish, cleanup is a breeze. No need to juggle multiple pots and pans—everything comes together in under an hour.

It’s also budget-friendly, using frozen or canned seafood, pantry staples, and a few dairy essentials. You can serve four to six people without splurging on specialty ingredients.

Versatility is another reason this casserole shines. You can mix and match seafood—use shrimp, scallops, imitation crab, or even canned tuna if that’s what you have on hand.

And finally, it’s a total crowd-pleaser. The creamy, savory base, combined with a golden, crunchy cracker topping, gives it that nostalgic, home-cooked vibe everyone loves.

As you’ll see below, the ingredients are simple but the flavor is anything but. Let’s break down what you’ll need.

Ingredients Notes

The charm of this dish lies in its balance of simple ingredients and rich flavor. Each component plays a role in making this casserole creamy, savory, and perfectly satisfying.

Seafood mix is the star here. I like to use a frozen blend of shrimp, scallops, and white fish. Thaw it overnight in the fridge or quickly under cold water before using. Imitation crab is a great budget option and adds a sweet touch.

The cream of mushroom soup brings body and earthy flavor. It forms the base of the sauce, creating that classic casserole texture. If you prefer, you can swap in cream of celery or even a homemade béchamel.

Sour cream and mayonnaise add tanginess and richness. The combo ensures the casserole stays moist during baking without being overly heavy. Greek yogurt is a lighter substitute if you're cutting back on fat.

Shredded cheese, like cheddar or Monterey Jack, adds a gooey, melty layer that makes every bite indulgent. Stir some into the mix and sprinkle a little more on top for good measure.

Don’t forget the buttery cracker topping. Crushed Ritz or Club crackers mixed with melted butter give the casserole its signature crunch. It's the final layer that seals in all the flavor and texture.

For equipment, you’ll need a 9x13 baking dish, a mixing bowl, and a spoon or spatula. No stand mixer, food processor, or specialty gadgets required!

How to Make This Easy Seafood Casserole

Making this casserole is as simple as mix, pour, and bake. Here’s how it comes together:

Start by preheating your oven to 350°F. While it heats, grease your baking dish with a little butter or nonstick spray. This helps everything come out clean and prevents sticking.

In a large bowl, combine your thawed seafood, cream of mushroom soup, sour cream, mayonnaise, and half the shredded cheese. Mix gently so the seafood stays intact but well-coated in the creamy mixture.

Once combined, pour the seafood mixture into your prepared baking dish and spread it evenly. Sprinkle the remaining cheese over the top for a bubbly, cheesy crust.

Now make the topping: crush about 1–1½ sleeves of buttery crackers and mix with melted butter. Sprinkle this generously over the casserole to create that perfect golden crunch.

Bake uncovered for 30–35 minutes, until the top is golden and the edges are bubbling. If you want extra browning, broil it for the last 2–3 minutes—but watch closely to prevent burning.

From start to finish, this dish takes under 45 minutes. Serve it hot, garnished with a sprinkle of parsley or a squeeze of lemon for brightness.

Storage Options

This casserole stores surprisingly well, making it ideal for meal prep or leftovers.

For refrigerator storage, let the casserole cool completely, then transfer to an airtight container. It will keep for 3–4 days. Reheat individual portions in the microwave or warm the entire dish in a 300°F oven.

To freeze, assemble the casserole (but don’t bake it), cover tightly with plastic wrap and foil, and freeze for up to 3 months. When ready to bake, let it thaw overnight in the fridge before popping it in the oven.

If you have leftover baked casserole, you can freeze it in individual portions. Wrap well and thaw before reheating in the oven or microwave.

When reheating, add a splash of cream or broth if the casserole seems dry. The topping may soften a bit, but a quick run under the broiler can help restore the crunch.

Variations and Substitutions

The beauty of this casserole is how easy it is to adapt. Whether you're short on ingredients or want to try something new, here are some delicious options:

Want to make it low-carb? Skip the cracker topping and use crushed pork rinds or a sprinkle of almond flour mixed with parmesan for crunch without the carbs.

For a spicy kick, add a dash of Old Bay, Cajun seasoning, or a spoonful of horseradish to the mix. You can also stir in diced jalapeños or a drizzle of hot sauce before baking.

Switch up the seafood to suit your taste or pantry. Canned tuna, leftover salmon, or even chunks of cooked lobster tail all work beautifully.

Make it more vegetable-forward by adding sautéed spinach, mushrooms, or peas. Just be sure to cook out any excess moisture first so the casserole doesn't get soggy.

Want to go dairy-free? Use a dairy-free cream soup, vegan mayo, and plant-based cheese. The texture will be slightly different, but still rich and satisfying.

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