Fish & leek gratin

• Frozen white fish fillets520g
• Leeks400g
• White potatoes700g
• Semi-skimmed milk400ml
• Plain flour30g
• Butter30g
• Mature cheddar80g

Plus salt and pepper. About £5.49 for the amounts used.

Method

1. 1

   Heat the oven to 200°C (180°C fan, gas 6).

2. 2

   Slice 700g potatoes thinly and boil for 6 minutes, then drain. Slice 400g leeks and fry in a little of the butter for 6 minutes.

3. 3

   Melt the rest of the 30g butter, stir in 30g flour, then gradually whisk in 400ml milk until thick. Stir in 50g of the grated cheddar and season.

4. 4

   Put the 520g fish (defrosted if frozen) in chunks in a baking dish with the leeks, pour over the sauce, then layer the potatoes on top and scatter with the remaining cheese.

5. 5

   Bake for 25 minutes until golden and the fish is cooked through.