In the meantime, pour the flour onto the kneading board, create a well in the middle and break the eggs into it, knead well until you obtain a smooth and even dough. Wrap the dough in cling film and let sit for 20 minutes.
Now clean the spinach and remove the stalks, keeping only the leaves. Boil them in a pot of salted water and when done, strain and wring them.
Finely chop the boiled spinach, add ricotta cheese, one egg, the grated Parmigiano Reggiano cheese and mix until smooth and even. Add a pinch of salt.
To give the tortelli their shape, roll out the dough, not too thin, using a rolling pin. Make 5 cm squares using a toothed pasta wheel.
Place a teaspoon of filling in the centre of each square. Make sure that your work surface and the dough are always well floured to prevent the dough from sticking.
Put another 5 cm square sheet of pasta over each dollop of filling and take care to seal the pasta well around the filling and along the edges so they do not come apart while cooking.
Cook the tortelli in plenty of salted water. Drain them well, taking care not to break them and to remove the cooking water.
In a serving bowl, dress the tortelli with melted butter and grated Parmigiano Reggiano.