Blanch spinach for a moment in boiling water then drain thoroughly.
Pre-heat oven to 190°C /400°F / Gas Mark 5 and place fillets on a clean flat surface. Season and lay on a generous layer of spinach.
Roll up, brush lightly with oil and arrange in greased ovenware dish.
Bake for 8 minutes.
Pre-heat grill to medium high and remove dish from oven.
Coat the tops with cream cheese (with snipped chives if wished) and place under grill until bubbling.