In a large skillet over medium-high heat, heat the olive oil. Then add the guanciale and cook until rendered, about 5 minutes. Add the garlic and cook for 6 minutes more, making sure that the meat does not get too crunchy and the garlic does not burn. If you see that the guanciale is browning too fast, remove it from the pan, finish the garlic and then add it again to the sauce.
Bring a large pot of salted water to a boil, add the pasta and cook about 6 minutes. Add the peas after the 6 minutes and cook until the peas are bright green, about more 2 minutes. Remove the peas and pasta to the guanciale sauce and saute for another minute or two. Then add the Parmesan and toss for 1 minute. Drizzle with the extra-virgin olive oil and some pepper. Serve with a bottle of robust red wine.
Taste before adding salt since the guanciale and Parmesan will also add salt.