Fill a large saucepan with water and bring it to the boil. Add a pinch of salt and the spaghetti, then cook until al dente, following the packet instructions. Before draining, reserve 200 ml of the pasta cooking water.
Meanwhile, peel the garlic cloves and slice them thinly.
Heat a large frying pan over medium-low heat and add a good splash of extra virgin olive oil. Add the sliced garlic and freshly ground black pepper, then fry for 2–3 minutes, until the garlic is lightly golden.
Drain the spaghetti and transfer it straight to the pan. Toss well to coat it in the oil, garlic and pepper.
Gradually stir in the grated Pecorino Romano, adding a splash of the reserved pasta water. Stir vigorously until the sauce emulsifies into a smooth, creamy coating.
If the sauce is too thick, add more reserved pasta water until it reaches the desired consistency.
Serve immediately, topped with extra grated Pecorino Romano and freshly ground black pepper, to taste.