100 g (3 1/2 oz) frozen spinach, defrosted, drained of excess water and roughly chopped
Put the potatoes into a large saucepan and cover with lightly salted water. Bring to the boil and cook for 18–20 minutes until tender.
Meanwhile, preheat the oven to 200°C (400°F), Gas Mark 6 and make the ricotta and spinach filling. Mix together the ricotta, lemon rind, nutmeg, wholegrain mustard, chives and spinach and season generously with salt and pepper.
Place the salmon fillets on a nonstick baking tray and score a slit horizontally along the centre of each fillet. Open out the slits and stuff each with the ricotta mixture. The mixture should fill the gap and create a little pile on top of each fillet.
Bake the fillets in the oven for about 15 minutes, or until the flesh flakes easily when pressed in the centre with a knife.
Drain the new potatoes, then return them to the pan, crush with a fork and season generously with salt and pepper. Serve the baked salmon with the crushed new potatoes, rocket leaves and lemon wedges.