Baked Haddock Casserole

Baked Haddock Casserole is a comforting, protein-rich seafood dish made with tender haddock fillets baked in a creamy egg mixture with tomatoes, onions, and melted gouda. It delivers the ease of a classic fish bake with the heartiness of a casserole, creating a simple, flavorful meal you can make any night of the week.

A Quick Look at the Recipe

✅ Recipe Name: Baked Haddock Casserole
🕒 Ready In: ~40 minutes
👪 Serves: 6 servings
🍽 Calories: ~220 per serving (estimated)
🥣 Main Ingredients: Haddock, eggs, tomatoes, onion, heavy cream, gouda cheese
📖 Dietary Info: Naturally low-carb and gluten-free
👌 Difficulty: Easy - sauté, whisk, assemble, and bake

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Unlike traditional baked haddock recipes that rely on breadcrumbs or butter sauces, this version bakes the fish directly in a savory custard-style mixture of eggs, cream, and vegetables for a richer, more satisfying result. The tomatoes add brightness, the onions build depth, and the gouda melts into a golden top layer that keeps the casserole moist and flavorful. It's naturally low-carb, high in protein, and a great way to turn a light white fish into a complete, filling meal.

If you're craving more comforting, no-fuss meals after trying this Baked Haddock Casserole, be sure to explore a few of our reader favorites. Start with Spinach Ricotta Stuffed Shells, Mini Meatloaves, Spaghetti Squash Casserole, or Pesto Tortellini for cozy dinners that come together with minimal prep.

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A Quick Look at the Recipe
Why You'll Love this Baked Haddock Casserole:
Key Ingredients:
Easy Substitutions & Variations:
How to Make Baked Haddock Casserole:
Recipe Notes & Tips:
How to Store:
Baked Haddock Casserole FAQs:
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Baked Haddock Casserole

Why You'll Love this Baked Haddock Casserole:

Simple, wholesome ingredients: Fresh haddock, eggs, vegetables, and cheese come together in a nourishing, flavorful meal.
Easy to prepare: No complicated steps, just sauté, mix, and bake.
Balanced and filling: Packed with protein and veggies, this bake is satisfying on its own or paired with a side salad.
Family-friendly: Mild haddock and melty cheese make this an approachable dish for all ages.
Great for leftovers: Reheats well for lunch or dinner the next day.

Key Ingredients:

haddock: Use fresh or thawed white haddock fillets. It's mild, flaky, and works well in casseroles without overpowering the other ingredients.
onion: Yellow onion adds savory depth and softens nicely during sautéing.
tomatoes: Fresh diced tomatoes bring acidity and moisture to the bake.
green bell pepper: Adds crunch and color, dice finely for quick, even cooking.
eggs: Bind the ingredients together while adding protein and structure.
gouda cheese: Melts well and adds a creamy, mild sharpness, can be swapped with Swiss or cheddar if needed.

Scroll to the recipe card at the bottom of this page for exact quantities.

Easy Substitutions & Variations:

Use a Different White Fish: Swap haddock for cod, pollock, tilapia, or halibut. Any mild white fish that flakes easily will work in this casserole.
Cheese Options: Gouda melts beautifully, but you can use mozzarella, Swiss, Monterey Jack, or a mild cheddar for a similar creamy finish.
Dairy Substitutions: Replace the heavy cream with half-and-half, whole milk, or full-fat coconut milk for a dairy-light or dairy-free option.
Vegetable Add-Ins: Bulk up the casserole with diced bell peppers, mushrooms, zucchini, or spinach. Just sauté them with the onions before baking.
Low-Carb Variation: Keep the casserole naturally low-carb by avoiding breadcrumb toppings and adding extra vegetables for volume.
Boost the Flavor: Mix in paprika, red pepper flakes, or fresh herbs like parsley or thyme to deepen the savory profile of the casserole.

How to Make Baked Haddock Casserole:

Preheat the oven to 400ºF. Grease a 9×13-inch casserole dish and set aside.
In a large skillet over medium-high heat, heat a drizzle of olive oil. Add the diced onion, tomato, and green bell pepper. Season with dried thyme and garlic. Cook for 5-6 minutes, until softened and fragrant.
In a large bowl, whisk together the eggs, milk, and heavy cream until well combined.
Add the cooked vegetables to the bowl and stir gently to coat.
Place the raw haddock fillets in the prepared casserole dish, then pour the egg and vegetable mixture evenly over the fish.
Sprinkle shredded gouda cheese over the top.
Bake uncovered for 25-30 minutes, or until the fish flakes easily with a fork, the eggs are set, and the cheese is golden and bubbly.
Let rest for 5 minutes before serving.

Recipe Notes & Tips:

Use fresh fish: Fresh haddock gives the best texture and flavor. If using frozen, thaw completely and pat dry before adding to the casserole.
Even cooking: Arrange the fish fillets in a single layer to ensure they bake evenly.
Don't overmix: When combining the vegetables with the egg mixture, stir gently to keep the texture light.
Check for doneness: The fish should flake easily with a fork and the egg mixture should be fully set in the center.
Cheese variations: Gouda adds a creamy, mild flavor, but cheddar, Swiss, or mozzarella can also be used.
Serving suggestion: Pair with a light side salad, roasted potatoes, or steamed vegetables for a complete meal.

A cheesy Baked Haddock Casserole slice with tomatoes, peppers, and melted cheese being served.

How to Store:

Refrigerator: Let the casserole cool completely, then transfer to an airtight container or cover the baking dish tightly. Store in the fridge for up to 3 days.
Reheat: Warm individual portions in the microwave or reheat the entire dish in a 350ºF oven for 10-15 minutes, or until heated through.
Freezer: Not recommended. The texture of the eggs, fish, and vegetables may become watery or grainy after freezing and thawing.

Baked Haddock Casserole FAQs:

What makes a Baked Haddock Casserole different from traditional baked haddock?

A Baked Haddock Casserole combines tender haddock fillets with a creamy egg mixture, vegetables, and melted cheese, creating a complete meal in one dish. Traditional baked haddock recipes usually rely on breadcrumbs or a butter sauce, but this casserole-style version is richer, more filling, and naturally low-carb. It turns a light white fish into a hearty, protein-packed dinner without needing side dishes.

Can I use frozen fish to make this Baked Haddock Casserole?

Yes. Frozen haddock works well in a Baked Haddock Casserole as long as it's fully thawed and patted dry before baking. Removing excess moisture helps the fish cook evenly and prevents the egg and cream mixture from becoming watery as it sets in the oven.

What other cheeses work well in a Baked Haddock Casserole?

Gouda gives this Baked Haddock Casserole a smooth, melty finish, but mozzarella, Swiss, Monterey Jack, or mild cheddar work just as well. Choose a cheese that melts easily so the top becomes golden and bubbly by the end of baking.