Get a saucepan, large enough to hold the 4 smoked haddock fillets in one layer, and add some water, the bay leaf, a whole peeled onion and a few peppercorns. Bring to the boil.
Place the fillets in the pan. As the water comes back to the boil, turn the fillets over to poach them on both sides. This should take a few minutes. When both sides are white and opaque, remove the fish from the pan.
Add the spinach to the boiling water and blanch for a minute or 2.
Crush a clove of garlic and add a couple of grinds of nutmeg, some fresh Italian parsley and plenty of salt and pepper, plus, a bit of the peppercorn mixture from the pan. Mix this with the spinach. Set aside.
For the hollandaise sauce, put the egg yolks and vinegar mixture in the small cup of a food mixer. Add the lemon juice and crushed peppercorns and bay leaf, and salt and pepper.
Whisk at high speed until it thickens and becomes pale yellow and fluffy. Turn down the speed and add the melted butter, sluicing it in a little at a time. Leave in the food mixer in a warm place to rest.
Lay out a slice of butter toast on each plate. Add the spinach mixture, then, put the haddock fillets on top.
Using the back of a spoon, spread the hollandaise sauce over the haddock.
Serving Suggestions: Serve with poached eggs, and sprinkled with a little paprika.