There’s something irresistible about the bubbling, golden top of a fresh-from-the-oven Seafood Casserole. Creamy, comforting, and packed with tender shrimp, flaky white fish, and a savory cheese sauce, this dish brings coastal flavor right to your dinner table—no fancy seafood restaurant required.

I started making this casserole on chilly Sundays when I craved something warm and luxurious without spending hours in the kitchen. It quickly became a family favorite, especially during holidays and gatherings when I wanted something a little special but still stress-free.

The best part? This easy seafood casserole comes together in under an hour with mostly pantry staples and frozen seafood. Let’s dive into why this dish is about to become a regular in your dinner rotation.

Why You’ll Love This Easy Seafood Casserole

Get ready to fall hook, line, and sinker for this comforting, crowd-pleasing casserole. It's the kind of recipe that feels indulgent but is secretly simple and efficient.

First off, it’s surprisingly quick and easy. While it tastes like something you'd order at a seaside bistro, you can have it prepped and in the oven in just 20 minutes. Most of the ingredients require minimal chopping or fuss—perfect for weeknights or last-minute guests.

It's totally budget-friendly, too. By using frozen seafood like shrimp and cod, you get all the luxurious flavor without the steep price tag. No need to splurge at the seafood counter—your freezer section has you covered.

It’s a one-dish wonder. This seafood casserole is hearty enough to stand alone, but also pairs beautifully with a side salad or steamed veggies. Fewer dishes, more satisfaction—what’s not to love?

And let’s not forget how customizable it is. Don’t like shrimp? Use scallops. No cod on hand? Swap in tilapia or even canned crab. This recipe is forgiving and flexible, making it ideal for busy home cooks.

Whether you’re hosting a dinner party or just feeding your hungry crew, this casserole brings elegance and ease to the same table.

Ingredient Notes

The beauty of this seafood casserole lies in its simplicity—humble ingredients come together to create something truly special. Here’s what makes this dish shine.

Let’s start with the seafood. I typically use a mix of shrimp and white fish like cod or haddock, both of which are mild and tender when baked. Frozen varieties work perfectly here—just thaw and pat them dry before using. The combo creates a lovely texture contrast: flaky fish and juicy shrimp in every bite.

The rich, velvety sauce begins with a simple roux made from butter and flour, which thickens up a base of milk and seafood stock. A little cream cheese melts into the sauce for extra richness and a touch of tang that complements the seafood beautifully.

To give the casserole depth and flavor, I add grated Parmesan and sharp cheddar cheese. The Parmesan brings a savory, umami kick, while the cheddar melts smoothly into the sauce. Don’t skimp on these—they help create that crave-worthy golden crust on top.

Aromatics like garlic and onion round out the flavor profile. Sautéed until soft and fragrant, they infuse the sauce with savory notes that balance the creamy richness and seafood sweetness.

As for the topping, I love using buttery breadcrumbs mixed with a little Parmesan. When baked, they create a perfectly crispy contrast to the creamy filling underneath.

Equipment-wise, you’ll need a medium saucepan for the sauce and a 9x13-inch baking dish for the casserole. A good whisk helps keep your sauce smooth and lump-free.

How To Make This Easy Seafood Casserole

Making this seafood casserole is as satisfying as eating it. Each step builds flavor and texture, so take your time and enjoy the process.

Start by preheating your oven to 375°F and lightly greasing your baking dish. This step ensures your casserole doesn’t stick and gets that lovely golden edge around the sides.

While the oven heats, begin your seafood prep. If using frozen shrimp or fish, thaw completely and pat dry with paper towels to remove excess moisture. Cut the fish into bite-sized chunks and set the seafood aside.

Next, melt butter in a saucepan over medium heat. Add diced onion and minced garlic, sautéing until softened and fragrant. Sprinkle in your flour and whisk continuously to form a roux—it should look like a thick paste and smell slightly nutty after a minute or two.

Slowly pour in milk and seafood stock, whisking as you go to prevent lumps. Let the mixture simmer gently until it thickens to a creamy consistency. At this point, stir in your cream cheese, cheddar, and Parmesan, letting them melt into the sauce until smooth.

Now it’s time to assemble. Spread your prepared seafood evenly in the baking dish, then pour the cheese sauce over the top, ensuring everything is coated. Gently mix if needed.

For that irresistible crunch, mix breadcrumbs with a bit of melted butter and extra Parmesan, then sprinkle the mixture evenly over the casserole. This will form a beautifully crisp, golden topping as it bakes.

Bake uncovered for 25–30 minutes, or until the top is golden and the edges are bubbling. Let it rest for 5–10 minutes before serving—this helps the casserole set up and makes for cleaner scoops.

Storage Options

This casserole stores wonderfully, making it ideal for leftovers or meal prep. Let it cool completely before transferring to airtight containers.

In the refrigerator, it keeps well for up to 3 days. Store in individual portions for easy reheating during the week.

You can also freeze it, either before or after baking. If freezing before baking, assemble the casserole in a freezer-safe dish, wrap tightly in plastic and foil, and freeze for up to 2 months. Thaw overnight in the fridge before baking as directed.

To reheat, use the oven or microwave. The oven (350°F for about 20 minutes) helps preserve that crispy topping, while the microwave works for quick single servings—just be sure to cover loosely to prevent splatter.

Variations and Substitutions

One of the best things about this seafood casserole is how easy it is to make your own. With just a few tweaks, you can suit any preference or dietary need.

Try swapping the shrimp and cod for scallops, crab meat, or even lobster if you’re feeling fancy. Just keep the total seafood amount around 1½ to 2 pounds for best results.

Not a fan of cream cheese? Use a few tablespoons of sour cream or even Greek yogurt for a lighter tang. You’ll still get a rich sauce with a different flavor twist.

For a more Mediterranean vibe, stir in some chopped spinach, sun-dried tomatoes, or olives before baking. These bold ingredients pair beautifully with the creamy base and seafood.

Prefer a gluten-free version? Use gluten-free flour for the roux and swap in gluten-free breadcrumbs for the topping. The texture and flavor will still shine through.

Want to bulk it up? Add cooked pasta or rice to the mix before baking. This turns the dish into a full one-pan meal and stretches the servings even further.

Don't be afraid to experiment. This is one of those recipes that welcomes creativity—it’s hard to mess up when everything starts with seafood and cheese!