Haddock au Gratin
Flaky haddock fillets blanketed in a creamy, golden-brown cheese sauce. This New England classic bakes up bubbly and rich, with a lightly crisped top that gives way to tender fish underneath. Serve it as a cozy weeknight supper or a fuss-free dinner party main.
For 4 servings
- prep
Preheat the oven and prep the dish.
Preheat oven to 375°F (190°C). Butter a 2-quart baking dish and set aside.
- boil · ~6 min
Poach the haddock fillets.
1.Bring 4 cups of water to a gentle simmer in a large skillet.2.Add lemon juice to the water.3.Slide in haddock fillets and poach gently for 5-6 minutes until just opaque.4.Remove fish with a slotted spatula and arrange in the prepared baking dish.TIPDon't boil hard — a gentle simmer keeps the fish tender and prevents it from breaking apart. - prep · ~8 min
Make the cheese sauce.
1.Melt butter in a medium saucepan over medium heat.2.Whisk in flour and cook, stirring constantly, for 1 minute until lightly golden.3.Slowly pour in warm milk, whisking continuously to prevent lumps.4.Bring to a gentle simmer and cook until thickened, about 3-4 minutes.5.Remove from heat. Stir in cheddar cheese, salt, black pepper, and nutmeg until smooth.TIPWarm the milk before adding — cold milk can make the sauce lumpy. - assemble · ~2 min
Assemble the gratin.
1.Pour the cheese sauce evenly over the poached haddock in the baking dish.2.Mix parmesan cheese with breadcrumbs in a small bowl.3.Sprinkle the breadcrumb mixture over the top. - bake · ~20 min
Bake until golden and bubbly.
Place the dish in the preheated oven and bake for 18-20 minutes, until the sauce is bubbling around the edges and the top is golden brown.
TIPFor a deeper golden crust, switch to broil for the last 2 minutes — watch carefully to prevent burning. - rest · ~5 min
Rest briefly before serving.
Let the gratin rest for 5 minutes. Garnish with fresh chopped parsley and serve hot.
What to keep in mind.
7 tips from the recipe — small details that make a real difference to the final dish.
- 1Pat the haddock fillets dry with paper towels before poaching for cleaner flavor.
- 2Use a wide skillet for poaching so the fillets sit in a single layer and cook evenly.
- 3Let the cheese sauce bubble gently; rushing on high heat can cause the dairy to separate.
- 4Taste the sauce before pouring it over the fish — add a pinch more nutmeg if you like warmth.
- 5If the breadcrumb topping browns too fast, tent loosely with foil for the remaining bake time.
- 6Let the gratin rest the full 5 minutes so the sauce sets and won't puddle on the plate.
- 7Leftover gratin keeps refrigerated for 2 days; reheat gently in a low oven to avoid drying the fish.
Adapt it for your goals.
Lighter Cream Sauce
Swap half the whole milk for low-fat milk and reduce cheddar to 3/4 cup. The sauce will be less rich but still smooth, cutting calories while keeping the gratin comforting.
Smoky TwistSmoky Twist
Replace 1/4 cup of cheddar with smoked Gouda and add 1/4 teaspoon smoked paprika. This gives the dish a subtle campfire note that pairs beautifully with the mild haddock.
Gluten FreeGluten-Free
Use a 1:1 gluten-free all-purpose flour blend for the roux and certified gluten-free breadcrumbs. The sauce will thicken the same way, and the topping stays crisp.
Herb GardenHerb Garden
Stir 1 tablespoon of chopped fresh dill or chives into the cheese sauce. It adds a fresh green lift that echoes the parsley garnish and brightens the gratin.
Why this is on our healthy list.
Lean Protein Source
Haddock provides high-quality, low-fat protein that supports muscle maintenance and repair, with about 20 g of protein per 150 g serving.
Rich in B Vitamins
Haddock is a natural source of B vitamins, including niacin and B12, which help convert food into energy and support nervous system health.
Calcium from Cheese
The cheddar and Parmesan add a good dose of calcium, which is essential for strong bones and teeth, in every serving.
Moderate in Saturated Fat
While this dish uses butter and cheese, the amounts are balanced so you get creamy satisfaction without excessive saturated fat when eaten as part of a varied diet.
Frequently asked questions
Yes, but thaw it completely in the refrigerator overnight and pat very dry before poaching, or the excess moisture will make the sauce thin.
