For the pasta, place the flour, egg and egg yolks into a food processor and pulse until well combined and the mixture comes together as a dough. Place the dough into a bowl, cover with cling film and place into the fridge to rest for 30 minutes.
Cut the pasta dough in half and feed one of the pieces through a pasta machine according to the machine instructions, ending on the thinnest setting.
Add the tagliarini cutter to the pasta machine and pass the pasta through the machine to make thin strips.
Repeat the process with the remaining dough, then dust the pasta with semolina flour, place onto a plate and refrigerate overnight.
When you're ready to cook the pasta, bring a large pan of salted water to the boil, add the tagliarini and cook for 2-3 minutes until tender.
For the sauce, heat the butter in a frying pan, add the spring onions and fry for one minute.
Add the peas and a splash of water and simmer for one minute, then add the prosciutto and cook for a further minute.
Drain the pasta and add to the pan with the sauce. Add the parmesan, season, to taste, with salt and freshly ground black pepper and stir. Serve immediately.