Put half of the butter in a pan and melt, add the shallots and cook until soft, but not browned.
Pour in the wine and let it bubble and reduce by about half.
Add the fish stock and let it reduce to about 150ml. Blitz with a stick blender, then whisk in the rest of the butter and the cream, and some seasoning. Set aside.
Cook the leeks in half the butter for about 15-20 minutes until softened, then add the cream and cook for another 4-5 minutes. Season and set aside in a dish.
Wipe the pan, reheat and add the rest of the butter and mushrooms and cook for a few minutes. Wilt the spinach in a pan.
Heat the frying pan, add the oil and when hot, put in the cod and cook for 5-6 minutes over a fairly high heat until browned on the underside and just cooked through. Reheat the sauce.
Spoon the creamed leeks on to 4 hot plates.
Add the spinach and some mushrooms. Put the cod on top, then garnish with a few more mushrooms. Spoon the hot sauce over and sprinkle with chopped chives.
Enjoy
Notes
Don't forget all profits are donated to Animal Rescue Charities.