Finely grate 50g of Parmesan and beat with the ricotta, then season with sea salt and black pepper. Spoon into a piping bag and place in the fridge while you roll out your dough. Follow the rolling-out instructions, taking the pasta to 1mm thickness.
Lay the sheets on a clean surface, then carefully pipe a ring of ricotta about 5cm wide, starting 2.5cm away from the edge of the pasta.
Separate an egg and carefully drop the yolk into the middle of the ricotta circle – it should fit snugly. Start your next ring of ricotta 5cm away from where your first one ends, then repeat 4 times more.
Brush the exposed pasta with water and carefully lay the second sheet of pasta over the top.
Starting at one end, gently press the pasta around the outside of the filling, pushing out the air and sealing the edges. Using a 10cm round cutter, cut out a circle-shaped ravioli with the egg right in the middle.
Check the edges are sealed – use a little more water to help, if needed. Place the ravioli on a large tray dusted with semolina, making sure they don’t touch and continue with the rest.
Bring a large pan of salted water to the boil, then reduce the heat to a rolling simmer. Carefully lower in the ravioli, two or three at a time, and cook for 4 minutes, or until they float.
Meanwhile, melt the butter in a frying pan over a medium heat. As soon as it foams, finely grate in the lemon zest and add a squeeze of juice plus a pinch of pepper.
Remove the pasta with a slotted spoon straight into the butter sauce, adding a splash of pasta water and grating in the remaining Parmesan. Cook the next batch of ravioli, then add to the sauce.
Dress the frisée with half the lemon juice and 1 tablespoon of oil, tear in the prosciutto, then season with pepper and mix together.
Divide the ravioli between your plates, arrange the frisée salad around it, then serve with a good grating of Parmesan.