- Heat the oven to 200°c/fan 180°c. Put the onions and tomatoes on a roasting tray and drizzle with balsamic vinegar and oil. Season well and roast for 30 minutes.
- Once cooked, tip into a large ovenproof dish with the orzo and spinach and mix together until the spinach has wilted down a little.
- Pour in the hot stock, season and add the basil. Cover with foil and transfer to the oven.
- Bake for 10 minutes, then uncover and nestle the cod fillets into the orzo. Cook for a further 20 minutes until the cod and pasta are cooked through.
- Serve with a drizzle of extra virgin olive oil, some more fresh basil and a scattering of parmesan.