Bring a saucepan of salted water to the boil. Add the noodles and blanch them for about 30 seconds, stirring with chopsticks to separate the strands. Drain immediately, reserving about 250ml (1 cup) of the cooking water.
Melt 60g of the butter in a large frying pan over medium heat. Add the black pepper and stir for 20–30 seconds, until fragrant and toasted.
Pour in about half the reserved cooking water, then add the noodles, miso and remaining butter. Turn off the heat, then add half the pecorino and season with a little sea salt.
Toss the noodles until the cheese melts and the noodles are well coated (if they seem dry, add some more of the reserved cooking water).
Transfer to serving plates and top with the remaining pecorino and, if you like, more pepper.
