Trim the stems off the spinach or Swiss chard and rinse the leaves well to remove any grit. Drop the leaves in boiling, salted water and remove just as soon as they have wilted, usually by the time the water comes back to the boil. Drain the leaves well, rinse off with cold water and squeeze them dry with your hands. Chop the leaves finely.

In sauté pan or skillet, gently sauté the garlic cloves in olive oil. When the cloves are lightly browned, remove them and add the chopped greens and let them simmer together, just for a few minutes so the greens absorb the flavor of seasoned oil, seasoning with salt and pepper as you go. Transfer the sautéed greens to a mixing bowl and let them cool.

Add the ricotta, grated Parmesan cheese, eggs and nutmeg to the bowl and mix everything together quite well. Add a heaping spoonful of flour and mix again. Taste for seasoning and, if it needs it, add a bit more salt. The mixture should be quite moist but hold together. If not, you can add another spoonful or two of flour.

Take a heaping spoonful of the mixture and, with well-floured hands, form it into a dumpling, which can be perfectly round, a bit flattened or in lozenges, as you prefer. Roll the dumpling in flour to cover and set it out on a well-floured baking sheet. Repeat until you've used up the mixture.

Poach your ravioli nudi in simmering salted water, draining them well with a skimmer when they come to the surface of the water. (The water should not be at a full boil, or they may well break apart.)

Serve your ravioli nudi right away, with the sauce of your choice (see Notes).