Cook the pasta in abundant salted water. When "al dente", do no drain it, simply transfer the pasta to a large bowl using tongs or a spaghetti spoon and reserve cooking liquid.
Add 2 ladles of the cooking liquid and about 3/4 of the grated Pecorino cheese. Toss well but gently so you do not break the spaghetti. Sprinkle 1 tablespoon of freshly grated black pepper over the pasta. If the pasta is too dry, add some more cooking water, if it is too runny, add some more cheese.
Portion onto 4 plates then serve right away extra grated Pecorino cheese.