Haddock & leek au gratin with sweetcorn mash

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.

  • Prep:10 mins
    Cook:50 mins
  • Serves 2
  • Easy

Nutrition per serving

  • kcal 618
  • fat 13g
  • saturates 6g
  • carbs 70g
  • sugars 20g
  • fibre 11g
  • protein 50g
  • salt 2.1g


  • 350g potatoes, quartered
  • 195g can sweetcorn in water
  • 240g bag ready-washed spinach
  • 2 leeks, thickly sliced
  • 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


  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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