Baked Haddock au Gratin

In Atlantic Canada and New England, fresh local haddock has long been a staple. Seafood restaurants along the North Atlantic coast serve batter fried haddock and chips or include haddock in chowders. But for home cooks wanting to “dress up” this delicious mild white fish, there is the classic “bubbly bake”. Home-style recipes for baked haddock vary widely from basic to fancy. But our recipe, for baked haddock au gratin incorporates the best of them all.

On beautiful Cape Breton Island you may be lucky enough to join the locals for a quaint evening of live Celtic music at a kitchen party. And on occasion, the aroma of fresh baked haddock au gratin will pierce the cool Atlantic air.

Taking baked haddock to the next level

There is a good reason why this recipe is popular with home cooks. Sure, haddock is delicious when battered and fried in a fish and chip meal. But that’s a style of cooking best suited for restaurants with deep fryers. However, I’m not a fan of messy deep frying at home. So, all the more reason to use the oven. This baked haddock recipe is easy to prepare and is sure to satisfy the whole family.

When people say, “I don’t like fish”, I think, maybe they haven’t tried this dish. Of all the fish in the sea, haddock is prized for being mild tasting, firm but flaky, lean and low in fat yet high in protein. This recipe combines haddock with cheese, toasted breadcrumbs and a creamy sauce made with mushroom soup. Adding fresh mushrooms, onion and red pepper, capers and seasonings brings it the next level.

A checklist of ingredients

After finding some fresh haddock, choose two decent sized filets, about 1½ pounds worth. Make sure you have all the other ingredients on hand. These will be commonly found in the kitchens of home-cooks.

• 1 small yellow onion, chopped
• ½ red bell pepper, chopped
• 3-4 medium-sized white mushrooms, sliced
• 1, 10 oz (284mL) can of condensed cream of mushroom soup.
• ¼ pound of butter
• 1 cup of whole milk
• 1 cup of grated cheddar or similar cheese (medium or old give more flavour)
• Sea salt, fresh ground black pepper
• Old Bay seasoning is a nice addition, if you don’t have any, make your own seafood seasoning using this copycat recipe

How to prepare haddock au gratin

This dish can be cooked as a one dish casserole then portioned out to serve. Or it can be divided into individual au-gratin dishes. Those typically oval, shallow stone-ware single-serving baking dishes are ideal as they allow crispy edges and browned crusts. With either option, make sure to grease them well first or apply non-stick cooking spray.

For the first layer we’ll add the haddock. If your fish is frozen, be sure it has thawed. While haddock fillets are usually sold skinless and boneless, you should still feel the flesh for any stray pin bones and remove them. Next, cut each fillet in half two make roughly square pieces. Pat them dry with a paper towel, then arrange them on the bottom of the greased baking dish. Fold thin pieces in half if needed. Sprinkle the fish with the salt, pepper and Old Bay seasoning.

Now, prepare the sauce. In a saucepan, sauteing the vegetables and then combine them with them with the condensed mushroom soup and milk. Next, prepare the breadcrumbs by tossing them with some melted butter. Continue layering our casserole by pouring the sauce mixture over the haddock. Next evenly distribute the shredded cheese. Then finally sprinkle the top with the buttered breadcrumbs.

Our casserole or au gratin dishes are now ready to bake. Since the single serving au gratin dishes are smaller, they will cook a little faster. Be sure to remove the dish from the oven as soon as it’s done to avoid it from becoming dry or rubbery. The ideal doneness is when the fish is completely opaque, tender, and flakes easily with a fork. The internal temperature of the haddock should read 145F (63C).

Garnish and serving suggestions

Once removed from the oven allow the dish to stand for a few minutes before serving. Accompany the plate with rice, mashed or riced potatoes, some seasonal steamed vegetables or coleslaw and some fresh crusty artisan bread. Either fresh parsley or dill sprinkled over the plate really compliment the meal. Offer some lemon wedges for those wanting to add extra zing to the dish.

Baked Haddock Casserole au Gratin

Kevin Lamoureux

Haddock is smothered in a creamy mushroom sauce then topped with cheddar cheese and breadcrumbs then baked until tender, bubbly and golden brown.

5 from 1 vote

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Prep Time 10 minutes mins

Cook Time 30 minutes mins

Course Main Course

Cuisine Canadian

Servings 4

Calories 260 kcal

Ingredients

  

• 1½ pounds haddock (2 filets)
• ½ tsp salt
• ½ tsp pepper
• ½ tsp Old Bay seasoning (optional)
• 2 tbsp butter
• ½ cup red bell pepper chopped
• ½ cup onion chopped
• 1 cup mushrooms sliced
• 10 oz can condensed cream of mushroom soup (284mL)
• 1 cup milk
• 2 tbsp capers (optional)
• 1 cup grated cheddar cheese

Topping

• ½ cup breadcrumbs
• 1 tbsp melted butter

Instructions

 

• Preheat oven to 375 °F and grease a 9×9” baking dish
• Pat dry the haddock with paper towels. Cut each filets in half then arrange in the baking dish. Sprinkle with the seasonings (salt, pepper, Old Bay).
• Melt the butter in a medium saucepan, add the red pepper and onions then sauté for about two minutes. Stir in the condensed soup, milk and mushrooms and heat until smooth.
• Pour the sauce mixture over the haddock. Then evenly distribute the capers.
• Sprinkle with the grated cheese.
• Mix the breadcrumbs with the melted butter then distribute evenly over the top of the casserole.
• Bake uncovered for 30 to 35 minutes or until the fish cooks and flakes easily. The topping should be golden brown.
• Remove from the oven and let stand 5 minutes before serving. Garnish with fresh parsley or dill and serve with lemon wedges.

Keyword casserole, haddock, seafood

Baked haddock in mushroom cheese sauce, originally published 1/22/2019. Revised and republished 3/11/2026

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