Cook pasta in large pot of boiling, salted water until al dente.
In a medium size sauce pan, heat olive oil over medium heat and add the chopped onion. Cook for approximately 5 minutes until translucent and then add the minced garlic. Cook for about another minute or two.
Add the can of peas with liquid to the onion garlic mixture and cook for another 5 minutes or so.
Strain the pasta leaving a small amount of the pasta water (maybe 1/2 cup) in the pot with the pasta. Transfer the pasta to a serving platter.
In a medium size bowl, beat the egg and add 1/4 cup of grated cheese, salt pepper and parsely to taste. Add to the pasta and mix well so that the egg coats the pasta. (Note: You don't want scrambled eggs, the egg will cook enough just from the heat of the pasta.)
Add the peas to the pasta and mix well.
Top with the other 1/4 cup of grated cheese. Of course you can always use more or less depending on your taste.
Serve with Italian Bread (I like Semolina) and side salad.