1

Preheat the oven to 180°C, fan 160°C, gas mark 4. Place the leeks in a lidded pan with the stock. Season and cook for 15 minutes until soft. Drain.

2

Wilt the spinach in a lidded pan then press out the excess liquid, chop and combine with the fromage frais in a bowl. Season and set aside.

3

Add the salmon and white fish to a pan of boiling salted water with a bayleaf. Cook gently for 5 minutes until the fish starts to flake. Lift out on to a plate and break into large flakes.

4

To make the white sauce, place the cornflour in a non-stick saucepan and gradually blend in the milk. Add the remaining bay leaf and bring to the boil, stirring until thickened. Add the lemon zest and juice, season and simmer the sauce for 5 minutes.

5

Cut the lasagne sheets in half, place in a bowl and cover with boiling water as per the packet instructions. Leave to soften for 5 minutes then drain.

6

To assemble the lasagne, spoon the drained leeks into the base of a 23 x 30 cm baking dish. Add half of the flaked fish and half of the prawns, drizzle with a quarter of the white sauce and then top with half the lasagne sheets.

7

Spread the spinach mixture over the lasagne sheets then add the rest of the fish and prawns. Top with the remaining lasagne sheets and pour the remaining white sauce all over the surface. Sprinkle with Parmesan. Bake for 30–35 minutes until the lasagne is bubbling and the top is golden brown. Leave to settle for 10 minutes before serving.