I've tried replicating the delicious cacio e pepe we had in Rome, at home -- three times. But no matter which recipe we use (Epicurious, Saveur, and the one from the restaurant we ate at in Rome), the pecorino clumps, instead of making a nice, creamy sauce. We're following the instructions to "stir vigorously until a sauce forms to prevent clumping" but it doesn't work!
I'm wondering what we're doing wrong - can someone help? Could it possibly be the type of cheese we bought? I bought a fairly expensive pecorino from Whole Foods, which I'm assuming is the "correct" type of cheese to use for this, but it doesn't seem to be working. We grated it coursely, the first time, and finely the other times -- but nothing worked.