Pastry board or large bowl, saucepan large enough for spinach.
SIFT the flour and salt on to a pastry board or into a large bowl. Make a well in the center and break in 5 eggs. Knead thoroughly, adding a little water if necessary, to make a smooth, pliable dough.
ROLL it into a ball, wrap it in a clean cloth, paper or foil, and leave it in the refrigerator to rest for 30 minutes.
CLEAN and wash the spinach carefully, but do not shake all the water off the leaves. Put it in a pan with a little salt, and cook over a moderate heat, covered, until tender. Take from the pan, and as soon as it is cool enough to handle squeeze dry and chop finely. Heat the butter in a frying pan, add the spinach and cook gently for a few minutes.
IN a bowl work the fresh Pecorino with a wooden spoon until soft and smooth. Add the eggs, Parmesan cheese, chopped spinach, salfron, and a good sprinkling of pepper and grated nutmeg, to taste Add more salt only if necessary. Mix thoroughly until well blended.
TAKE the dough from the refrigerator. Divide it into two equal-sized pieces and roll them both out into sheets, as thinly as possible. On one of the sheets place little heaps of the prepared stuffing, equally spaced apart. Cover with the remaining sheet of dough and press together very firmly between the mounds. Cut between the rows with a pastry wheel or a sharp knife to make ravioli about 1+ inches square.
HAVE ready a large pan of rapidly boiling salted water. Drop in the ravioli a batch at a time (this type is not meant to dry first). They will be ready almost as soon as they rise to the surface. Drain well and serve hot, with generous portions of meat or tomato sauce, and grated Pecorino cheese.