Delia Smith Cod Mornay

I first made Cod Mornay on a Tuesday night when I had absolutely no business making anything that involved a béchamel sauce. It was one of those dreary, drizzly evenings when you’re tempted to eat toast in your dressing gown — but I had cod that needed using, and a stubborn desire to feel like a grown-up. And look, it wasn’t perfect. The sauce was a bit lumpy (rookie mistake), and I absolutely overdid the cheese. But it was delicious.

There’s something wonderfully old-school about this dish. It feels like the kind of thing you’d be served at a fancy hotel in the ’70s, but without the snootiness. Creamy, cheesy, buttery sauce wrapped around flaky cod, with a layer of soft greens underneath and a golden, crunchy topping — it’s comfort food dressed up for company. Delia’s version keeps it simple, but leaves plenty of room to play.

These days, I make it when I want something warm, rich, and deceptively quick. No drama, no faff — just proper food, with flavour that wraps around you like a woolly jumper.

Why You’ll Love It

• Ready in just over half an hour, but tastes like a weekend effort.
• Creamy cheese sauce + buttery cod = magic — no need to oversell it.
• Uses kitchen staples — milk, butter, flour, cheese, sorted.
• Easy to adapt with different greens or fish.
• Great way to sneak kale into people who say they hate kale.
• Leftovers reheat surprisingly well, especially if you crisp them up.

Ingredients

• 600g cod loin or fillets (skin off)
• 80g kale (or spinach, if kale’s not your thing)
• 80g butter
• 80g plain flour
• 1 litre milk (full-fat or semi-skimmed)
• 250g cheddar cheese, grated
• 25g breadcrumbs (panko if you’re feeling posh)

How to Make It

Prep the fish and greens:

Chop the cod into chunks — big enough so they don’t vanish in the sauce, but small enough to cook quickly. Lay them in a single layer in an ovenproof dish. Scatter the kale over the top — no need to wilt it first, it’ll soften in the oven.

Start your roux (but don’t rush it):

Melt the butter in a saucepan over low heat. Once melted, stir in the flour and cook it gently for a couple of minutes — just enough to lose that raw flour smell. You’re after a smooth, buttery paste.

Turn it into a silky sauce:

Slowly, and I mean slowly, pour in the milk, whisking like mad as you go. Don’t dump it in all at once or you’ll end up with lumpy regret. Once all the milk’s in, keep whisking over low heat until it thickens to a proper sauce. Like custard, but savoury.

Cheese it up:

Take the sauce off the heat and stir in half the cheese until it’s melted and dreamy. A pinch of salt and a twist of black pepper here won’t go amiss.

Layer it on thick:

Pour the cheese sauce over the fish and kale. Make sure everything’s covered — use a spatula to nudge the sauce into the corners if needed. You want every bite to have a bit of everything.

Crunchy topping, golden finish:

Sprinkle the rest of the grated cheese and all the breadcrumbs on top. Pop the dish in the oven at 200°C (or 400°F) for 20 minutes, until the top’s bubbling and golden.

Cool just a bit, then dive in:

Let it sit for five minutes so the sauce can settle. Serve with something to mop up the extra sauce — crusty bread, mash, or even just a spoon.

Common Mistakes and How to Dodge Them

Why is my sauce lumpy?
You probably added the milk too quickly or didn’t whisk enough. No shame — next time, go slower. A balloon whisk is your best mate here.

My fish turned mushy. What gives?
Overbaking! Cod cooks fast. Stick to 20 minutes max once the sauce is on.

It tastes bland — help!
Cheddar varies wildly. Use a strong, mature one — mild cheddar gets lost. A bit of Dijon mustard in the sauce also helps sharpen things.

Sauce split after reheating. Can I fix it?
Add a splash of milk and warm it slowly, stirring gently. Or just embrace the rustic charm and call it “deconstructed.”

Storage and Reheating

Fridge:
Let it cool fully, then cover and refrigerate for up to 2 days. It’s great the next day.

Freezer:
Portion it into freezer-safe containers and freeze for up to 3 months. Defrost overnight in the fridge before reheating.

Reheat:

• Oven: 180°C for 15–20 mins, covered with foil. Remove foil for the last few minutes to crisp the top.
• Microwave: Works in a pinch — cover with a damp paper towel and heat in 1-minute bursts.

Frequently Asked Questions

Can I use frozen fish?
Yes — just defrost it fully and pat dry before using. Otherwise the dish might go watery.

What’s the best cheese for Mornay sauce?
Classic cheddar works great. Gruyère or Emmental are dreamy too. Just avoid overly oily cheeses like mozzarella.

Can I add more veg?
Definitely. Cooked leeks, steamed broccoli, or peas all slot in beautifully.

Can I make this ahead of time?
Yup — assemble it all, cover, and refrigerate for up to 24 hours. Bake just before serving.

Nutrition Facts (Per Serving):

Calories: 781 kcal
Fat: 48g
Carbs: 34g
Protein: 53g
Sugar: 13g
Sodium: 773mg

More Delia Smith Recipe:

• Delia Smith Smoked Mackerel Pâté
• Delia Smith Macaroni Cheese
• Delia Smith Cheese And Onion Pie