Boil the spaghetti in a large pot with plenty of salted water.
Meanwhile, grate a generous amount of tuna roe.
Peel two cloves of garlic, cut them in half and remove the inner green shoot.
Coarsely chop the garlic and place it in a serving bowl.
Squash the garlic with a fork against the inside of the bowl, add 4 tablespoons of olive oil and the grated tuna roe.
Mix everything together with a wooden spoon.
Once you’ve drained the spaghetti, pour them into the bowl, grate the remaining tuna roe, add the chopped parsley, drizzle with P.D.O. Sardegna oil, toss and serve.