Sift the all-purpose flour with the semolina flour, pour them on a wooden board and make a well in the centre.
Break in the eggs and add a good pinch of salt and a tablespoon of olive oil.
Mix the flour and the eggs with a fork until crumbly, then knead the dough, adding cold water if needed.
Keep on kneading, more and more, as to develop the gluten which will give strength to the sheets of pasta. After a while the dough should have the right consistency: smooth, velvety and no longer sticky.
Wrap it in plastic film and let it rest for 30 minutes at room temperature.
Now prepare the filling. Drain and press the spinach dry, then chop them finely with a knife. Add the fresh ricotta cheese and the grated Parmigiano. Mix thoroughly with a fork and season with a good pinch of salt and some grated nutmeg.
Now roll the dough. The most important thing, whether you’re using a classic long rolling pin or a pasta machine, is to roll it over and over again, rolling and stretching it as much as you can.
Make a paper thin wide sheet of pasta.
Put little mounds of spinach and ricotta filling – about one teaspoon each - at regular intervals onto the strips. Fold the sheet of pasta to cover the filling and press gently with your fingers all around the filling, to seal it. With a scalloped pastry cutter cut the ravioli, leaving about an inch of pasta all around the filling. Put the ravioli onto a floured tray in one layer.
To cook the ravioli bring a large pot of water to the boil, salt the water and pour a tablespoon of extra virgin olive oil in it: this will prevent ravioli from sticking to each other.
Cook ravioli in batches, according to the size of the pot. When they rise to top, which will be in less than 5 minutes, remove them gently with a large slotted spoon and place them on a large deep plate.
Melt a knob of butter in a small pan with some sage leaves until they get crisp. Pour the brown butter and the sage leaves over the ravioli, sprinkle with a lot of grated Parmigiano and serve immediately.