Spinach-wrapped Fish Fillets in Pastry Parcels

These golden puff pastry parcels look pretty and are exciting to eat with the layers of buttery spinach purée and tender white fish inside them. It takes a little time to wrap each one up but I find it quite fun as you can do it peacefully in advance and keep the parcels in the fridge until you want to cook them. They make a much more substantial main course than you would imagine and are best se