I use two kinds of peppercorns in this cacio e pepe. The black ones are tingly and strong, and the citrusy pink ones balance the creamy cheese sauce. I throw in some chard so the cook (um, me) doesn’t have to make a salad, too.
Bring a large pot of water to a boil for the pasta.
In a large skillet, heat the oil, two turns of the pan, over medium. Add the onion and garlic; season with salt and half the ground peppercorns. Cook, stirring often, until the onion softens, 3 to 4 minutes. Add the chard. Cook, stirring often, until wilted, about 2 minutes. Add the nutmeg. Reduce heat to a simmer.
In a large bowl, mix the cheeses.
Salt the boiling water and add the pasta. Cook until 1 minute shy of the package directions. Scoop out about 1 cup of the pasta cooking water, then drain the pasta. Whisk the cooking water into the bowl with the cheeses. Add the pasta and chard. Toss until coated; season with salt. Top with the remaining peppercorns.