For the pasta, mix the flour and semolina together on a clean work surface or in a large bowl. Make a well in the centre and break in the eggs. With a fork or with your hands, gradually mix the flour with the eggs to form a soft dough. Knead the dough for 5 minutes, or until smooth. Shape the dough into a ball, wrap in cling film and leave to chill in the fridge for at least 30 minutes.
Flour the pasta machine with semolina and divide the pasta into 4 equal pieces. Starting at the lowest (thickest) setting, feed one piece of the dough through the machine, turning the handle with one hand and holding the dough as it comes through the machine with the other. Change the setting on the pasta machine to the next-thickest setting, flour it again and feed the pasta sheet through the machine again, as before.
Repeat this process 3-4 more times, flouring the machine and changing the setting down each time. The pasta should be quite thin, but still easy to handle without tearing. Don’t be tempted to skip settings or the dough may tear. Repeat with the other pieces of dough. Once the pasta sheets have reached the ideal thickness, dust with semolina and set aside.
For the spinach and ricotta filling, bring a pot of water to the boil and add the spinach. Cook for 2 minutes, or until wilted. Remove from the pot and drain. Put in a tea towel and squeeze to drain any moisture, then finely chop. Mix all of the filling ingredients with the spinach, except the beaten egg, until well combined. Leave in the fridge to firm up slightly.
For the sage butter sauce add the stock into a hot pan, then add the butter and get it hot and foaming. Add the sage leaves, giving them a good squeeze before you drop them in to release their oils. Cook for 2-3 minutes.
To make the ravioli, put a pasta sheet on your board and place a heaped teaspoon of the ricotta mixture at equal intervals along the pasta. Brush a little of the beaten egg around each filling then lay another pasta sheet on top and carefully press down around each filling ball to remove any air. Cut in squares with your ravioli cutter or knife, then dust with semolina flour and set aside.
To cook the ravioli bring some water to the boil and a good pinch of salt (the water should be as salty as the sea). Drop the ravioli in to the water in small batches and cook until the float to the surface, then add them to the sage sauce. You can add a little of the pasta water to the sage sauce to get a creamy consistency.
Serve in warmed pasta bowls with a grating of Parmesan.