Chop spring onions and fry in small knob of butter.

Meanwhile, heat grill and boil pasta as per instructions

Once spring onions are cooked, add the mackerel (in flakes with skin removed) and creme Fraiche

Season to taste and add cooked pasta

Pour pasta mixture into grill proof dish and sprinkle the Parmesan cheese over the top

Put in grill and remove once brown on top