For the pasta dough
Place flour, salt and olive oil in the bowl of a mixer and blend for a few minutes. Add eggs and egg yolk and continue to mix until a soft, elastic dough is formed. Leave the dough to rest for 30 minutes.
For the filling
Heat the butter in a pan, add the spinach and cook for a few minutes until it becomes wilted and all juices evaporate. Chop spinach and transfer to a bowl. Mix in the prosciutto, feta cheese, basil, salt, pepper and nutmeg and set aside.
Divide the dough in two and roll out each piece until it is very thin (almost transparent). Brush the sheets of dough with a bit of water and, working in straight lines, place 1 tsp of filling after another leaving 5 cm distance between each. Cover with the other sheet of dough and press gently between the filling to adhere the two sheets together.
Cut out 6 cm circles around each spoon of filling making sure the edges of the ravioli are tightly sealed.
Place the ravioli in boiling salted water and cook for 2-3 minutes until al dente and strain.
Heat the butter in a large frying pan, until slightly colored. Add the ravioli, chili, basil leaves and mix well. Sprinkle with crumbled feta cheese and serve.