Haddock & leek au gratin with sweetcorn mash

Haddock & leek au gratin with sweetcorn mash

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(11 ratings)

Prep: 10 mins Cook: 50 mins


Serves 2
Leek and spinach are layered up with white fish fillets and cheese sauce then topped with golden mash in this delicious, low-fat oven bake.

Nutrition and extra info

  • Freezable

Nutrition: per serving

  • kcal618
  • fat13g
  • saturates6g
  • carbs70g
  • sugars20g
  • fibre11g
  • protein50g
  • salt2.1g
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  • 350g potatoes, quartered



    The world's favourite root vegetable, the potato comes in innumerable varieties. A member of…

  • 195g can sweetcorn in water


    sw-eet corn

    Also known as corn on the cob, sweetcorn is composed of rows of tightly packed golden yellow…

  • 240g bag ready-washed spinach



    Used in almost every cuisine across the world, spinach is an enormously popular green vegetable…

  • 2 leeks, thickly sliced



    Like garlic and onion, leeks are a member of the allium family, but have their own distinct…

  • 300ml skimmed milk, plus 3 tbsp
  • 15g unsalted butter
  • 15g plain flour
  • ½ tsp English mustard
  • 75g mature reduced-fat cheese, grated
  • 2 x 125g fillets of skinless haddock



    A white-fleshed salt water fish often compared with cod in flavour and texture. Found on the…


  1. Heat oven to 200C/180 fan/gas 6. Boil the potatoes for 15-20 mins until tender, then drain. Reserve 3 tbsp corn and blitz the rest (with its juice) using a hand blender or a food processor until completely smooth, then mash into the potatoes. Cook the spinach following pack instructions – if you have a microwave, choose this method.

  2. Put the leeks in a pan with the 300ml milk and the butter. Cook gently, part-covered, for 8 mins until the leeks are tender. (Keep an eye on things as milk can easily boil over.) Mix the 3 tbsp milk with the flour and mustard, then stir into the leek mixture – keep stirring until thickened. Take off the heat and stir in three-quarters of the cheese.

  3. Squeeze as much liquid as you can from the spinach, then arrange on the base of 2 gratin dishes. Place a fish fillet on top of each, then spoon over the leek & cheese sauce. Top with the sweetcorn mash. Mix the remaining corn and cheese, and scatter on top. Place the dishes on a baking tray and cook for 25 mins until the fish flakes when tested and the top is golden.

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Comments, questions and tips

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Suffolk Primrose
17th May, 2020
Not really for me. But OH quite liked so... prep time definitely much more 30-40 mins. Proportions not right - way too much sauce (though tasty if you add much more cheese and mustard) & not enough mash. And fish got lost. And without much texture (panko breadcrumbs did help) it was just a pile of leeky slop. Sorry!! Much nicer and so much quicker/ simpler to poach smoked haddock, add creamy mash and asparagus/ broccoli.
mercuryzelda's picture
11th May, 2018
My husband and I liked this dish, but it was a bit too much faff for a simple dinner for two, and didn't have a lot of texture. (I even used red potatoes and left the skins on, and left the sweetcorn whole, and it helped a little but not much.) I also agree that it takes a lot longer to prep than the suggested 10 minutes. The flavours were certainly lovely, but all in all, it didn't seem worth the time put in.
Jemma Ward's picture
Jemma Ward
21st Feb, 2018
Brilliant easy tea recipe. Used smoked haddock, added some frozen pees to the leek mix and also panko breadcrumbs on top to give it a bit of texture. Would definitely make again!
24th Sep, 2015
10 mins prep is way under. It took me 40. Even if you're fast, unlike me, allow 25 min
19th Jul, 2015
My partner gave this 9 out of 10 so it must have been good! Recipes on here rarely get that high a mark. I made it in one largish baking dish and didn't bother pre-cooking the spinach (why would you when it goes in the oven for 25 mins?!) Also used a lot more (full fat, mature) cheddar and served with green beans and peas. I rated it 5 out of 5 and am sure to make again Best to use the best quality sweetcorn - jolly green giant, for the most flavour IMHO.
6th Oct, 2014
Absolutely yummy. I added the sweet corn to the leeks & added peas as well. Thumbs up!
28th Aug, 2014
4, 6 and 10 yr old gave this double thumbs up. Happy days
28th Aug, 2014
Made this to the recipe for hubby and I, children were most put out, we had to share some out. All loved it, so will double up and make in 1 bigger dish, rather than individual dishes. Disagree with comments on sweetcorn mash, it was lovely...!
21st Aug, 2014
Really tasty. Loved the sweetcorn mash!
18th Aug, 2014
I've made this a couple of times now, the first time followed it to the letter. We didn't like the sweetcorn mash, it had a funny texture and colour and we didn't feel it added anything to the dish. Second time made a basic white sauce and added cheese then stired it into the leeks which I sauteed in a little butter and just made ordinary mash and felt it was better. Also 2nd time used smoked haddock which was nice.
15th Aug, 2014
Hi, can you tell me what size gratin dishes you used for this? Want to make as it looks so delicious, but not sure what size to buy. Thanks.
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